I know this is a rather old topic, but I may be able to help. I have Shift running without any problems on R2. In fact, I just reinstalled it the other day.
I have two questions for you –
1. What video card do you have and what version driver for it? My R2 computer is now my HTPC computer with an ATI HD6450 video card. I had problems with Shift continuously crashing while starting. I discovered that it had to do with some of Catalyst software. I uninstalled ALL Catalyst software and installed ONLY the video card driver. I have had no problems since.
2. What error code are you receiving?
As a side note, I used to have an nVidia GTX 260 video card in this machine and had no problems at all.