for checking computer parameters "everest" is good ... launch the program, right click on the computer icon, fast report, normal text ... now save it to file and upload it on rapidshare/megaupload/hotfile/etc
well those are basics :
- install new graphics card drivers
- install program "game booster" (or any similar one) - it closes unnecessary programs in task manager while playing a game...
- defragmentation of your drives
- scan your drives for viruses/spyware
- reinstall DR (or copy from your friend his already installed game at dvd-r and then just copy it to your drive)
Pretty time taking and not sure if it helps (because there are tons of possibilities that may cause it) but in ur place i would do it all ... imo its probably ur system fault (because GMs fixed the problem with memory leak) so first u need to do is make it shine ;p (and on the other hand you will not need to do it later .. so its not useless even if it wont help

)..
about the game booster and similar programs ... if you know all processes that you can close manually in task manager you dont need to install itAfter you do that all ... let me know if something changed