Well on the other hand that could also be the issue as some of the updates DO provide compatibility fixes.
I mention the SP1 issue because it appears (to me) that it did cause ME1 to "break" and using compatibility mode fixes it. However if I had to choose between a single game and SP1, SP1 would always win hands down.
So, even though I appear to be contradicting myself (install updates, yet SP breaks ME) I would still suggest installing all the important updates and the compatibility fixes and use compatibility mode for the game as system stability and security is more important to me than a single game.
Will this fix your current issue with ME1, I don't know. It's just a cautionary statement.
BTW..... Tips on Troubleshooting Game Issues - item #4
The other things you could do is update your DirectX files - items 5 & 6
Make sure you install the latest patch(es) - item 3
My two cents