PSD file deleted mid-save

Question

I've had this occur twice now in the last 24 hours:
Upon editing a large PSD file (1.2gb) and starting a save, photoshop hung and was not responding for over 20 minutes.
I cancelled the save, and later closed the file.
The PSD file was then deleted entirely, I discovered.
It also no longer appeared in the recent documents list.
As a note, I am saving the files to a network drive and have no trouble with other files at the moment.
I am using 5.1.
Any reason behind this, any way to recover the PSD?

Answer 1

This is the boilerplate text often used in connection to saving to a network (please NOTE the part where it explains that normally, it does work, but that it is impossible to troubleshoot someone else's network remotely, and that's why it's not supported by Adobe):
If you are opening files over a network or saving them to a network server, please cease and desist immediately in the event you are currently experiencing problems with one or more files. Working across a network is not supported.
See: 
http://kb2.adobe.com/cps/406/kb406793.html
  Copy the CLOSED file from your server to your local hard disk, work on it, save it again to your local hard disk, close it, and copy the closed file back to the server.
     Of course, the fact that Adobe does not support working across a network does not necessarily mean it won't work.   It should.
    Adobe's position is that there are too many variables in a network environment for them to guarantee that everything will work correctly in every network, especially given the fact that if something does not work properly, it's probably the network's fault, and Adobe has no way of troubleshooting your network.
  If you can't work locally, you are on your own, and if something happens, you're on your own. If you must work from a server, make sure your network administrator is a competent professional.
When problems arise, a lot of valuable work can be lost.
Wo Tai Lao Le
我太老了          (No connection to Adobe)