it's your virtual memory file for that drive. right-click on My computer, select properties, click the advanced tab, then performance options, click the 'change' button under Virtual Memory, and delete the values for the drive you want to format. these instructions are for win2k cause it's what i use, but winxp shouldn't be too different. restart your pc if necessary.
but if you're trying to format your system drive from windows while windows is running, then good luck with that. haha
