I'm starting to think that may be my problem. I've had an examination of the rules.txt, but can't yet find a looped tech requirement. Could someone please have a look at this (taken from my rules.txt) and tell me if they can see one?
Advanced Flight, 4,-2, Rad, Too, 3, 0 ; AFl
War Fever, 5,-1, nil, nil, 3, 2 ; Alp
Amphibious Warfare, 3,-2, E1, Tac, 3, 0 ; Amp
Science Drive, 4,-1, Uni, Phi, 3, 3 ; Ast
Atomic Physics, 4,-1, ToG, MP, 3, 3 ; Ato
Automobile, 6,-1, Ref, Che, 3, 4 ; Aut
Banking, 4, 1, Tra, Rep, 1, 1 ; Ban
Bridge Building, 4, 0, nil, nil, 0, 4 ; Bri
Home Front, 6, 0, nil, no, 3, 0 ; Bro
Basic Religion, 5, 1, nil, nil, 0, 2 ; Cer
Steel Production, 5,-1, Uni, Eng, 2, 4 ; Che
Malay Tech, 4,-1, nil, no, 3, 0 ; Chi
Code of Laws, 4, 1, nil, nil, 0, 2 ; CoL
Air Supremacy, 5,-1, Mob, AFl, 3, 0 ; CA
Submarine Tech, 2,-1, Stl, MP, 3, 0 ; Cmb
Communism, 5, 0, Eng, nil, 2, 2 ; Cmn
Electronics, 4, 1, X5, Cor, 3, 4 ; Cmp
Infantry Training, 7,-1, nil, nil, 2, 0 ; Csc
Adv. Construction, 4, 0, Mas, Cur, 3, 4 ; Cst
Corporation, 4, 0, Eng, Eco, 2, 1 ; Cor
Currency, 4, 1, nil, nil, 0, 1 ; Cur
Democracy, 5, 1, Ban, nil, 2, 2 ; Dem
Economics, 4, 1, Uni, Ban, 2, 1 ; Eco
Naval Tech 1, 4,-1, Che, Tac, 3, 0 ; E1
American Cities, 2, 0, no, no, 3, 2 ; E2
Industrialization, 6, 0, RR, Ban, 2, 1 ; Eng
Imperialism, 3,-1, Mon, Tac, 3, 2 ; Env
Allied Unity, 5, 1, FP, Phi, 3, 2, ; Esp
Land Surveying, 5, 0, nil, nil, 2, 4 ; Exp
Desperate Tactics, 4,-1, nil, nil, 3, 0 ; Feu
Flight, 4,-1, Che, Tac, 2, 4 ; Fli
Militarism, 3,-2, no, no, 3, 2 ; Fun
Allied Solidarity, 3, 0, Lit, Dem, 3, 2 ; FP
British Morale, 4, 0, Lit, FP, 3, 2 ; Gen
Chindit Resistance, 4, 0, nil, nil, 3, 0 ; Gue
x, 1, 0, no, no, 0, 0 ; Gun
Aust. Volunteers, 4,-1, nil, no, 3, 0 ; Hor
Soviet Cities, 2, 0, no, no, 3, 2 ; Ind
Brit/Indian Cities, 2, 0, no, no, 3, 2 ; Inv
Manchurian Tech, 4,-1, nil, no, 3, 0 ; Iro
High War Morale, 4,-1, MP, Phi, 3, 0 ; Lab
Pacific Domination, 4,-1, Env, Pla, 3, 2 ; Las
Chinese Tech, 4,-1, no, no, 3, 0 ; Ldr
Allied Morale, 5, 0, Dem, Alp, 3, 2 ; Lit
Machine Tools, 4,-2, Che, Tac, 2, 0 ; Too
Adv. Aeronautics, 4,-1, CA, Nav, 3, 0 ; Mag
Mass Plane Prodctn.,6,-1, CA, Cor, 3, 4 ; Map
Modern Construction,4, 0, nil, nil, 3, 4 ; Mas
Advanced Alloys, 5, 0, Aut, Cor, 3, 4 ; MP
Exp. Armor Design, 4,-2, U2, ToG, 3, 0 ; Mat
Moving Pictures, 4, 1, nil, nil, 3, 2 ; Med
Amphibious Vehicles,6,-2, Amp, Mob, 3, 0 ; Met
Naval Bays, 4,-1, E1, Too, 3, 4 ; Min
Mobile Warfare, 8,-1, Aut, Tac, 3, 0 ; Mob
Monarchy, 5, 1, Cer, CoL, 0, 2 ; Mon
Organized Religion, 5, 1, Cer, nil, 1, 2 ; MT
Taoism, 4, 0, Cer, nil, 0, 2 ; Mys
Adv. Air Strikes, 6,-1, AFl, Ast, 3, 0 ; Nav
Nuclear Fission, 6,-2, Ato, MP, 3, 3 ; NF
Naval Engineering, 6,-1, Stl, Cmp, 3, 0 ; NP
Wartime Ideology, 6, 1, Tac, Env, 3, 2 ; Phi
Australian Vehicles,4,-1, nil, no, 3, 0 ; Phy
Japanese Devotion, 2,-1, Phi, Fun, 3, 0 ; Pla
Pearl Harbor Attack,4, 0, nil, nil, 3, 2 ; Plu
High Octane Fuel, 4, 0, CA, NP, 3, 4 ; PT
Agriculture, 4, 1, nil, nil, 0, 1 ; Pot
Radio, 5,-1, Fli, X5, 3, 4 ; Rad
Railroad, 6, 0, Bri, nil, 2, 1 ; RR
Maritime Culture, 4, 1, nil, nil, 0, 1 ; Rec
Refining, 4, 0, Cor, nil, 2, 4 ; Ref
Refrigeration, 3, 1, X5, San, 3, 1 ; Rfg
Republic, 5, 1, Cor, nil, 0, 2 ; Rep
Vectored Trajectory,5,-2, Too, Mob, 3, 0 ; Rob
Divine Wind, 6,-2, Feu, Mag, 3, 0 ; Roc
Sanitation, 4, 2, nil, nil, 2, 1 ; San
Steel Plane Casing, 6,-1, MP, Mag, 3, 4 ; Sea
Colonial Economics, 4, 1, Gen, Eco, 3, 1 ; SFl
Supr. Aeronautics, 6,-2, PT, Sea, 3, 0 ; Sth
Long-Range Bombers, 4,-1, Sth, X6, 3, 0 ; SE
Naval Tech 2, 4,-1, E1, MP, 3, 0 ; Stl
Mass Power Source, 4, 1, Cmp, Exp, 3, 4 ; Sup
Tactics, 6,-1, Csc, nil, 2, 0 ; Tac
Imperial Loyalty, 3,-1, MT, Las, 3, 2 ; The
Research Edge, 4, 0, Ast, MP, 1, 3 ; ToG
Trade, 4, 2, Cur, CoL, 0, 1 ; Tra
University, 5, 1, nil, nil, 1, 3 ; Uni
Japanese Offensives,4,-1, nil, nil, 3, 0 ; War
Indian Patriation, 4,-1, nil, nil, 3, 0 ; Whe
Lingua Franca, 4, 2, nil, nil, 2, 3 ; Wri
Future Technology, 1, 0, ToG, Lab, 3, 3 ; ...
Cruiser Design, 4,-1, Stl, ToG, 3, 0 ; U1
Improved Armor, 4,-1, Mob, MP, 3, 0 ; U2
Heavy Naval Guns, 4,-1, X2, NP, 3, 0 ; U3
French Tech, 4,-1, nil, no, 3, 0 ; X1
Battleship Design, 4,-1, U1, NP, 3, 0 ; X2
Unique Japanese CV, 4,-1, no, no, 3, 0 ; X3
Unique American CV, 4,-1, no, no, 3, 0 ; X4
Electricity, 4, 0, nil, nil, 2, 4 ; X5
Imp. Bomber Engines,4,-1, PT, Rob, 3, 4 ; X6
Automotive Industry,4, 0, MP, nil, 3, 1 ; X7
Advanced Flight, 4,-2, Rad, Too, 3, 0 ; AFl
War Fever, 5,-1, nil, nil, 3, 2 ; Alp
Amphibious Warfare, 3,-2, E1, Tac, 3, 0 ; Amp
Science Drive, 4,-1, Uni, Phi, 3, 3 ; Ast
Atomic Physics, 4,-1, ToG, MP, 3, 3 ; Ato
Automobile, 6,-1, Ref, Che, 3, 4 ; Aut
Banking, 4, 1, Tra, Rep, 1, 1 ; Ban
Bridge Building, 4, 0, nil, nil, 0, 4 ; Bri
Home Front, 6, 0, nil, no, 3, 0 ; Bro
Basic Religion, 5, 1, nil, nil, 0, 2 ; Cer
Steel Production, 5,-1, Uni, Eng, 2, 4 ; Che
Malay Tech, 4,-1, nil, no, 3, 0 ; Chi
Code of Laws, 4, 1, nil, nil, 0, 2 ; CoL
Air Supremacy, 5,-1, Mob, AFl, 3, 0 ; CA
Submarine Tech, 2,-1, Stl, MP, 3, 0 ; Cmb
Communism, 5, 0, Eng, nil, 2, 2 ; Cmn
Electronics, 4, 1, X5, Cor, 3, 4 ; Cmp
Infantry Training, 7,-1, nil, nil, 2, 0 ; Csc
Adv. Construction, 4, 0, Mas, Cur, 3, 4 ; Cst
Corporation, 4, 0, Eng, Eco, 2, 1 ; Cor
Currency, 4, 1, nil, nil, 0, 1 ; Cur
Democracy, 5, 1, Ban, nil, 2, 2 ; Dem
Economics, 4, 1, Uni, Ban, 2, 1 ; Eco
Naval Tech 1, 4,-1, Che, Tac, 3, 0 ; E1
American Cities, 2, 0, no, no, 3, 2 ; E2
Industrialization, 6, 0, RR, Ban, 2, 1 ; Eng
Imperialism, 3,-1, Mon, Tac, 3, 2 ; Env
Allied Unity, 5, 1, FP, Phi, 3, 2, ; Esp
Land Surveying, 5, 0, nil, nil, 2, 4 ; Exp
Desperate Tactics, 4,-1, nil, nil, 3, 0 ; Feu
Flight, 4,-1, Che, Tac, 2, 4 ; Fli
Militarism, 3,-2, no, no, 3, 2 ; Fun
Allied Solidarity, 3, 0, Lit, Dem, 3, 2 ; FP
British Morale, 4, 0, Lit, FP, 3, 2 ; Gen
Chindit Resistance, 4, 0, nil, nil, 3, 0 ; Gue
x, 1, 0, no, no, 0, 0 ; Gun
Aust. Volunteers, 4,-1, nil, no, 3, 0 ; Hor
Soviet Cities, 2, 0, no, no, 3, 2 ; Ind
Brit/Indian Cities, 2, 0, no, no, 3, 2 ; Inv
Manchurian Tech, 4,-1, nil, no, 3, 0 ; Iro
High War Morale, 4,-1, MP, Phi, 3, 0 ; Lab
Pacific Domination, 4,-1, Env, Pla, 3, 2 ; Las
Chinese Tech, 4,-1, no, no, 3, 0 ; Ldr
Allied Morale, 5, 0, Dem, Alp, 3, 2 ; Lit
Machine Tools, 4,-2, Che, Tac, 2, 0 ; Too
Adv. Aeronautics, 4,-1, CA, Nav, 3, 0 ; Mag
Mass Plane Prodctn.,6,-1, CA, Cor, 3, 4 ; Map
Modern Construction,4, 0, nil, nil, 3, 4 ; Mas
Advanced Alloys, 5, 0, Aut, Cor, 3, 4 ; MP
Exp. Armor Design, 4,-2, U2, ToG, 3, 0 ; Mat
Moving Pictures, 4, 1, nil, nil, 3, 2 ; Med
Amphibious Vehicles,6,-2, Amp, Mob, 3, 0 ; Met
Naval Bays, 4,-1, E1, Too, 3, 4 ; Min
Mobile Warfare, 8,-1, Aut, Tac, 3, 0 ; Mob
Monarchy, 5, 1, Cer, CoL, 0, 2 ; Mon
Organized Religion, 5, 1, Cer, nil, 1, 2 ; MT
Taoism, 4, 0, Cer, nil, 0, 2 ; Mys
Adv. Air Strikes, 6,-1, AFl, Ast, 3, 0 ; Nav
Nuclear Fission, 6,-2, Ato, MP, 3, 3 ; NF
Naval Engineering, 6,-1, Stl, Cmp, 3, 0 ; NP
Wartime Ideology, 6, 1, Tac, Env, 3, 2 ; Phi
Australian Vehicles,4,-1, nil, no, 3, 0 ; Phy
Japanese Devotion, 2,-1, Phi, Fun, 3, 0 ; Pla
Pearl Harbor Attack,4, 0, nil, nil, 3, 2 ; Plu
High Octane Fuel, 4, 0, CA, NP, 3, 4 ; PT
Agriculture, 4, 1, nil, nil, 0, 1 ; Pot
Radio, 5,-1, Fli, X5, 3, 4 ; Rad
Railroad, 6, 0, Bri, nil, 2, 1 ; RR
Maritime Culture, 4, 1, nil, nil, 0, 1 ; Rec
Refining, 4, 0, Cor, nil, 2, 4 ; Ref
Refrigeration, 3, 1, X5, San, 3, 1 ; Rfg
Republic, 5, 1, Cor, nil, 0, 2 ; Rep
Vectored Trajectory,5,-2, Too, Mob, 3, 0 ; Rob
Divine Wind, 6,-2, Feu, Mag, 3, 0 ; Roc
Sanitation, 4, 2, nil, nil, 2, 1 ; San
Steel Plane Casing, 6,-1, MP, Mag, 3, 4 ; Sea
Colonial Economics, 4, 1, Gen, Eco, 3, 1 ; SFl
Supr. Aeronautics, 6,-2, PT, Sea, 3, 0 ; Sth
Long-Range Bombers, 4,-1, Sth, X6, 3, 0 ; SE
Naval Tech 2, 4,-1, E1, MP, 3, 0 ; Stl
Mass Power Source, 4, 1, Cmp, Exp, 3, 4 ; Sup
Tactics, 6,-1, Csc, nil, 2, 0 ; Tac
Imperial Loyalty, 3,-1, MT, Las, 3, 2 ; The
Research Edge, 4, 0, Ast, MP, 1, 3 ; ToG
Trade, 4, 2, Cur, CoL, 0, 1 ; Tra
University, 5, 1, nil, nil, 1, 3 ; Uni
Japanese Offensives,4,-1, nil, nil, 3, 0 ; War
Indian Patriation, 4,-1, nil, nil, 3, 0 ; Whe
Lingua Franca, 4, 2, nil, nil, 2, 3 ; Wri
Future Technology, 1, 0, ToG, Lab, 3, 3 ; ...
Cruiser Design, 4,-1, Stl, ToG, 3, 0 ; U1
Improved Armor, 4,-1, Mob, MP, 3, 0 ; U2
Heavy Naval Guns, 4,-1, X2, NP, 3, 0 ; U3
French Tech, 4,-1, nil, no, 3, 0 ; X1
Battleship Design, 4,-1, U1, NP, 3, 0 ; X2
Unique Japanese CV, 4,-1, no, no, 3, 0 ; X3
Unique American CV, 4,-1, no, no, 3, 0 ; X4
Electricity, 4, 0, nil, nil, 2, 4 ; X5
Imp. Bomber Engines,4,-1, PT, Rob, 3, 4 ; X6
Automotive Industry,4, 0, MP, nil, 3, 1 ; X7
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