Revo uninstaller does not "use" any restore points. Vista creates one whenever you install or uninstall anything. Because of the funny message you are getting when you want to write a restore point, I suggest you first check whether you have any. Do the following: Go to All Programs > Accessories > Command Prompt > right click on Command Prompt > Run as Administrator => into the little black window type: VSSADMIN LIST SHADOWS . Shadows = Restore points are dated. Make sure you have the ones for C:\ that you are looking at.
I am not sure what Sandboxie and a new program installation mean in this context (your last sentence).

I posted on sandboxie last week. Doesnt work. Tried everything my limited knowledge of computing allows. Installs fine, but just wont work. Thanks for the system restore reply.

No. When i first got my pc i remember installing sandboxie and it worked. It disappeared somehow (dont ask) so i know it should work. Very frustrating.