I have Photoshop CS 5.1 32bit and 64bit (running on 64bit windows), and sometimes it happens that I can't open files (jpg, psd, ...) in it. When I drag and drop a file to photoshop, or click on Open file dialog, or even try to make a new document, nothing happens.
I have tried tricks with deleting preferences, but it didn't help. The only thing that helps is restarting windows - but this is not a practical solution for me.
I would expect some help from Adobe on this, since we pay a lot for their products!
Unfortunately this is a forum for the CommunityHelp application and not a Photoshop forum, so there isn't a way to get an answer here.
Might I suggest that you describe your problem in a Photoshop forum such as:
You can see a list of all Photoshop forums at:http://forums.adobe.com/community/photoshop
Adobe Community Help and Learning team