hmm very strange, if I try to run it with the Race 07 desktop shortcut which points to (C:\Games\Steam\Steam.exe -applaunch 8600) I get the popup, if I try to launch with the GTR-E shortcut (C:\Games\Steam\Steam.exe -applaunch 8660) or STCC shortcut (C:\Games\Steam\Steam.exe -applaunch 8690) it appears to run, I don't get the popup, Steam Friends shows me in-game (for a few seconds) but it never actually starts and the Race_07 process doesn't show in Task Manager.
I've just verified the integrity of all 3 installations and they were all OK.
I deleted the .blob files but then rebooted into Win7, it worked OK in Win7 the first time but second time it wouldn't start up and I had the popup again, I rebooted back in to XP and it was working OK again. It seemed to be related to the shutdown issue with MotecAdd DX but as I said in the MotecAdd thread that issue has been fixed anyway with an update. So far it's back to normal.