Yes I recognize this sort of problem… I assume you have VISTA ??? Anyway, mostly if you restart your pc, than there is a chance the file is gone… You have tried to delete the file in DOS and it did not worked out for you very well, mostly you have to do this as an administrator in safe mode… if you experienced problems deleting the file…
This a problem many people have pointed out, if they wanted to delete files that are simply Left Overs* from a movie they were encoding… They consume a lot of hard drive space… I am not sure if this is the case with you…
Anyway, if safe mode and a restart did not work out well for you, you can try the program KYLE has pointed out for you…