I've always been a Splinter Cell fan, so when I heard about Conviction I started stumbling over myself with excitement

I rented it for the 360 before the PC download was available just because I have no problem spoiling it for myself.
Played through and beat the story on realistic in one night. Sure it's a short story, but it was a very good one, lots of things I never expected to see were revealed. The game play was different, but fantastic.
So now I've finally got the PC version, which looks a heck of a lot better on my wide-screen monitor, and I've run into a problem. Every time I quit the game I have to restart the computer to get it to start again. No doubt this has something to do with that copy protection thing. Does anyone know what to do about this? I don't know very much about this DRM thing, any help would be appreciated.
On a side note, would anyone like to join me for some online co-op?