Windows – Unresponsive file causes Windows Explorer to stop responding

I've run into an issue while trying to play Titan Quest: Immortal Throne (a legit copy, purchased on Steam) on my laptop. It's an HP Pavilion, Intel CORE i3, Windows 7 Home Premium x64, 4 gb RAM, Intel 4600 graphics card. It is a problem only with the game, but I'm not sure if the game is crashing as a result of the file becoming unresponsive, or if the file becomes unresponsive because the game crashes, but I'm leaning towards the former.

After playing anywhere from 2 minutes to an hour, the game goes "not responding." There is no obvious "trigger" that causes it, it has happened while speaking with merchants, fighting monsters, running around in town, looking through the skill trees, and so on. I have tried waiting for the game but it never comes back, so I just close the program.

I decided I was going to poke around at the save files based on my suspicion that it was having trouble interacting with them which was causing the problem. I attempted to copy the save game folder so I had a backup, but the little copy progress pop-up got stuck on "Discovering items" with the time remaining, items remaining, and speed all displaying "calculating" and never changed. Clicking the "cancel" button just left it sitting there saying "canceling" as the progress bar was moving but nothing happens. Attempts to delete the save game folder result in the same thing. After a restart, I was able to copy the save games out and continue.

I opened the folder and began deleting pieces out of it to try to isolate the problem file. In the save game folder (located in the My Documents area), there is a folder for each character, and in each character's folder there is a file called "Player.chr" and any attempt to do anything with this file causes Windows Explorer to go "not responding" after the game has previously gone "not responding." If I restart my computer, I can mess with the "Player.chr" file as you would normally be able to (copy, move, delete, so on).

After the game goes "not responding" and the save file becomes unresponsive, I have not found any other issues or strange occurrences with any programs or files on the computer, it seems to be isolated to that file. When shutting down or restarting though, Windows displays the "Windows is waiting for the following programs to shut down" window, but there is nothing in the window.

Things I have tried:
-Patching the game to the unofficial patch (no change)

-Deleting the save altogether and starting new with a different character (no change)

-Verify integrity of the files with Steam, 4 times (no problems found, no change)

-Uninstalling and reinstalling the game, 4 times now (no change)

-Using the "Unlocker" program I already had installed on the unresponsive "Player.chr" (program finds no issue with the file, but attempting to delete it using the program causes the program to go "not responding")

-Running the Steam/Titan Quest in Windows XP compatibility mode and as an Administrator (no change)

-Altering the game to run on multiple cores (no change)

-Using "Log off" instead of restarting after a crash (file was still unresponsive after logging back in)

-Tried playing on lower graphical settings (no change)

-Using a version of the game installed from discs instead of downloaded through Steam (for some reason the save files are named differently after playing them from the disc install, but same result)

Is there anything I can do to make the file respond again short of restarting? Even if it wouldn't solve the problem, something that could replicate whatever the effect of restarting the computer has on it (making the file no longer "in use"?) would satisfy me at this point.

Any suggestions or help would be greatly appreciated. I've tried 5 tech forums now and yet to receive any serious response. I have friends playing it currently and telling me how good it is, but it's been hard to enjoy or make any real progress in given the issue.