Might try copying the psd to your HD if you haven't already. Then opening it.

Also there other programs that can open PSD files other then just adobe. You might try that to see if the problems lies within the relation between the file and PS.

One free software that will open PSD files is IRFanView. Incase you don't have another software that opens PSD files.

Sorry to hear about the problem. Hope something works out for you. I don't have problems with mutil-sessions, but I don't use RW's either. Again hope at least one of the things suggested by all works.