Do you have to process the file right away? Can you do Merlyn's original suggestion: copy the file somewhere temporary and come back to it. If it matches the incoming file, its done, handle and delete. If not, try again. Puts you off one 'check for incoming' loop at first but you're already waiting a half hour, so its not 'real time' critical.

We use a checkfile process, if the file's the same size/un-touched for some # of minutes, it's considered done. Guess part of this may be what the fallout is of handling half done files vs. the need for speed.

a