My children found that this is often caused by an error in
one of the support folders. Have you added any new SIMS,
if they do not install properly then you get this
symptom. Otherwise we had to remove all of the support
guff to a "spare" folder and bring them back one at a time
until the faulty one(s) were found. If you can find out
anything that works you can ignore that thread. It is a
back breaking job, so if anyone knows better.....