well i would say its a problem with Dirt 2. since its the only game you have a problem with right? you have no other hardware/software related problems?
you could run some benchmarks and some test to stress the computer to see if it shows up anything out of the blue.
also do you have any problem with 1080p playback? if not id say its just that game.
maybe others here will have other ideas to help.
also im not sure if this will help you out. but you can bypass the startup videos...
you can just rename these three:
AMD_sting.bik rename to _AMD_sting.bik
ego_sting.bik rename to _ego_sting.bik
intel_sting.bik rename to _intel_sting.bik
Just add an underscore ( _ ) to the front of the name.
The "donuts" video (sting.bik or sting_us.bik) MUST run or the game will stall when that video is intended to run, it runs just before the "Start" page and is also an idle time video and runs when the game is idle.
For the sting.bik or sting_us.bik, which one is used depends on your location. You should replace this with any very short video, the game may stall if a 0 length video is used.
I replaced the sting_us.bik with a 1 second video created from the original. You could instead use a blank black screen video that is 1 second in length.
Backup your original sting.bik/sting_us.bik file before doing the following.
Get
RadTools, load the video into the RadTools app, convert it to an .avi file, load that into MS MovieMaker or any other video editing program, crop (cut) the video down to 1 second in length.
When using RadTools to convert to .avi you can choose the frame compression method. "Full frame uncompressed" does not always work and Windows may not be able to read the result. The "Mpeg4" or "XVid" compressed format almost always works well.
I cut the video to display just the "DiRT2" text image seen at the end of the original video. Save the .avi, open it in the RadTools app, press the "Bink it" button and create a new sting_us.bik (or sting.bik) file.
Put that file into the .../DiRT2/video folder.
Another hint: RadTools can be used to re-encode bik videos including changes to frame size and frame rate. This might be useful for those who are having trouble with skipping or freezing videos.
The easy remedy is to re-encode the bik video to a small frame size like 640x480 and maybe to change the video compression level that Bink uses. The best compression to use can only be determined by experimentation, try the default first.