It's not my system, since I've spent the last two months installing about 50 of the 100+ PC games I own, and documenting the problems I've come across, and so far there have been very few (hint: the few problems have all been related to the copy protection schemes some games are using).
What you're apparently not aware of is that the download version of rFactor uses online activation, while the 1.255 version that comes on DVD uses SafeDisc copy protection (which is why I'm required to have the disc in the drive to play the game while you are not). So it looks like the SafeDisc protection that comes with rFactor 1.255 DVD version has compatibility issues with Windows 7.
My rig:
Win7 x64 RC v7100
Intel Q6600 running at 3.6Ghz
8GB RAM
1TB HD x 2
BFG 280 GTX 1Gig
Ageia PhysX PCIe card
Logitech Driving Force racing wheel/pedals (x64 Logitech driver installed)