How can I tell what files are currently open by a process (i.e. my app)?

I am using a Lucene.Net index and want to give the user an option to move the index, but am having trouble closing it down so the directory/contents can be moved (I keep getting access denied exceptions). I need to be abl开发者_JAVA百科e to have some more information so I can debug this problem, such as being able to tell what files are currently open, and as much information about each use as possible.

Alternatively, is there any way to simply force close a bunch of files so they can be moved? This would make things a lot easier to solve.

You can use Process Explorer to find out which process has opened a file.