SOLVED: Uphclean fixed the problem
Basically the comp in question is taking ages to log out - but only from the main account. I tried creating another account on the system and it only took seconds to log out. However, there seems to be no specific reason for this. Could it be that the registry is fragmented or something? How would I test what the problem is?
EDIT: I forgot to mention that this has been happening for quite long now. The computer is not usually used by me. Also, there are no problems logging in, only logging out.