Just do an advanced search under system folders, hidden folders, and sub folders for "sfcfiles.dll". Then highlight each file, one at a time, and hit F2 and change the name to "sfcfilesold.dll". You will get a warning from windows that this is a necesary file but just ignore it. Restart your computer and then you can delete Xerox and nwwia. I learned this on Annoyances.org.

download this program from systernals.com called process explorer. open it click on find and find handle. search for nwwia. it will be in the winlogon.exe. right click on C:\program files\xerox\nwwia and click close handle. you can now delete the xerox folder