redseujac wroteI agree completely, Tullik.
It was a Registry problem.
Running the Startup Manager messed up some registry entries concerning some services.
Jouni could tell us what the problem (BUG) really was (I'm rather curious to know...).
The bug was rather simple: one component used the following API call to open a registry key: OpenKey(path, True); The "True" parameter is what caused all the problems, it tells Windows that if a registry key we are trying to open doesn't exist it should be created and then opened. As a result, while the component was only supposed to read data, it by accident created registry keys.
It's usually very safe to create registry keys, usually only removing or modifiying registry keys or entries can cause damage but in this case it seems that Vista couldn't handle the additional registry keys created by accident.
The actual component containing this bug wasn't written by me but an otsourced developed from who we bought the component. I did browse the code through, tested and accepted it so at the end it is in fact my fault that this bug was in the program.
This bug was the very first serious bug we have had in years, and the very first ever of its kind (i.e. a bug that caused problems with user's computer even if the user didn't touch the Delete button) and I do apologize for that. We are now planning to take new measures to make sure this will be the last a problem this serious ends up in our product.