[oscarjh]

Legs,
Just a hunch (if you have not done this already).
1) Back-up your league folder to a temp folder (cut and paste).
2) Start the game and open your created league (if it's not already the default league)
3) Go to League > League Setup and once there, press "Run computer Manager on all teams"
4) Try to sim

If that does not work:
1) Copy your backup over the existing file (OOTP folder)
2) Repeat 2 and 3 above
3) Choose edit schedule, then generate schedule
4) Try to sim

I'm assuming that you have not been able to sim any games yet. If you have, generating a new sched. will not work.

Good luck!