The log is likely relative to the Users folder (Docs and Settings in XP, User); if it isn't then try creating a Documents and Settings folder to give it a place to write to.
However, you absolutely need to install 3.0.1 first no matter what OS, then you use the second disc to patch to 3.3.1 for Non-XP32 bit systems.
But, to answer your direct question. I would first try removing the C:\Windriver directory completely. I think this is all you need to do, I don't think anything in the registry would cause you trouble for reinstalling.
Also, there is an issue with installing WindRiver on windows 8! See the instructions for the work-around
http://wpilib.screenstepslive.com/s/...elopment-tools