All icons the same (picture viewer?)

Assuming that it isn't a virus (!) - run your anti-virus and malware/adware scans first. Download the reg file from the link below:-

http://www.winhelponline.com/articles/105/1/File-association-fixes-for-Windows-Vista.html

The reg file for icons is:-

http://www.winhelponline.com/fileasso/lnk_fix_w7.zip

Don't worry that it might say Vista, it works with Win7.

Hopefully this will fix it it, if not, (and System Restore doesn't work - a last resort), you have to create a new user with administrator rights and then delete your old user (but it's a while since I had to do that).