When I place a file in a particular folder, it gets deleted within a few seconds. I think there is some process that is doing something with the data in the file and then removing the file. What's the simplest/fastest way I can find out what's accessing the file after I drop it in the directory?
You could probably enabling auditing and see what user account is accessing the file...that might help:
Or you can run wireshark or Process Monitor: http://technet.microsoft.com/en-us/sysinternals/bb896645 and watch real-time what is occuring. That would be the way I would go...starting with Process Monitor.