Desktop background wont display

Hi, been reading these forums for a while now, but never had a need to post... until now :confused.

Basically, I accidently ran ComboFix when I was trying to unistall it after I'd successfully run it to clear a malware/spyware problem a few weeks ago. Since then (upon the restart after the accidental run) my desktop background has become blank (as shown in the attached pic) and I'm unable to change it, unless I go through 'set as background' in Firefox.



Also, certain other images are also now blank. One example of this is when dragging files to the recycle bin, as shown in the pic below:



I'm running Vista Home Premium with SP2 on Dell Inspiron 1520. Any help would be greatly appreciated