WooHoo! The Icons are fixed!
Many thanks to Brink, Arc, and D3ftOn3Z for their helpful suggestions.
For anybody else who's run into a similar problem and want's to know how i fixed it, I simply tried the easiest suggestion first which for me
was Step 3 in Arcs' post, Download and replace the Imageres.dll file, delete the Icon Cache & Thumbnails files, then reboot the PC
...considering i checked out the icons inside Imageres.dll and found them to be modified by the Alienware theme, i was reasonably sure this was the file that needed replacing back to original. I was not sure if registry entries were modified also - it seems not as everything is back to normal by following the above steps.
- Thanks everyone.