Mark Russinovich at www.sysinternals.com has released freeware utility Handle which
lets you answer that question - which program has a particular file or directory
open? Useful to Windows NT admin.
Handle For Windows NT is targetted at searching
for open file references, so if you do not specify any command-line parameters
it will list the values of all the handles in the system that refer to open
files and the names of the files.