What act are you in, and have you been to the battlefield yet this act?
Were you previously able to load any of the saves that now have a problem?
Usually *.tmp folders mean that for some reason the game was not successfully completing the save process. If your saves were working up until your RAM problem, though, that would not be the case here (at least not directly).
The game saves files to a temporary folder before moving them to a folder without the .tmp extension. This is to prevent a working save from being damaged if there is a problem during the save process when overwriting an existing save.
Windows has been know to decide game files have become corrupt after a crash, even if the game was not involved. It is possible memory problems interfered with the save process, or Windows may have simply 'fixed' your working saves after the crash until they no longer worked. One person had Windows delete all of the inv.b2 files in their DD saves when another program crashed 5 minutes after exiting that game (fortunately it is a zero byte file, so was easy to replace).
In Windows Explorer, browse to the '
..\Beyond Divinity\savegames' folder, and check the number of files in the .tmp folders. There should be 22-23 files in a save before entering the BF that act, and 28-30 afterwards. If you have less than this, post the list of the files you do have, along with where the save is in the game.
Depending on the file, missing files might be replaceable with corresponding ones from the next most recent working save, though this might cause other problems, and it doesn't sound like you have any working saves.
Also, select all of the files in a save folder, right click and select Properties. In the windows that comes up, check if the files are marked as Read-Only (no checkmark in 9x or green box in XP; don't select a folder in XP to check this, though, as it always displays the green box, rather than actually scanning through the contained files and any subfolders).
With the English 1.49
patch, you no longer need the play CD in a drive.