Hmm, the only other suggestion I have is to try clearing the temp and user directories (note that this will destroy all your current sketches so you need to keep a copy of the directories before replacing them. When making new parts I often manage to get Fritzing totally hung and the only solution I've found is to delete these two directories (Fritzing will recreate them on restart if you rename them to move them aside):
(which is a hidden directory so you need to have show hidden directories set in explorer) and
where user_name is your windows account name. If something gets corrupted in here (usually sketches but maybe also parts search) Fritzing sometimes won't recover from it (it also sometimes forgets to delete files it should which may be part of the problem). I've never seen this problem on my installations but they are all win7 pro. It may also
be illuminating to start the debug log as mentioned above and see what that says (its usually gibberish to me, but in this case it may show something of interest ).