In reply to mypyrex:
For me this can be the problem from Hell, and has at times taken me weeks to resolve.
I eventually resolved the error with trial and error, much in the same way you are doing it. You could even try Windows Task Manager (Win7 keys are CTRL+up arrow button+ESC) forgotten how to do this in Vista and XP.
You could try the printer software as well, but its all a guessing game for me, at least, till the print jobs are purged.
Sorry