Sorry, I'm not currently connected on internet from home
No problem, it's not urgent.
I don't have default theme. It's downloaded from here, and with my own picture.
You're using your own skin? That's interesting. Maybe your skin has some settings that make the program crash, but I'm not aware of the problem because the other skins don't have the same settings and thus don't crash. Personally, I rate all the movies that I watch, and I never have a crash.
For a while, the program didn't crash. Were you using this skin all the time?
My backup file in "My Documents" directory is more than 21 mb large. Maybe that is the problem.
The backup files can't be a problem. 21 mb of backup files certainly means that you have hundreds of them.
BTW can i delete anything from there without disrupting all wished, owned, rated... etc movies?
Backups are a safety in case you current coollection file gets corrupted. You probably don't need to have so many backups. You can delete the older ones, as there's little chance that you'll ever use them.