Hard drive permissions problem

Hey,

I have Windows XP Home, and I have to put my hands up that I screwed around with the drive permissions. No surprise windows wouldn’t boot and the install disc couldn’t write to the drive, so I installed another windows partition. I booted it in safe mode and took ownership, then changed the permission of the Unknown Account {S-1-…} (which i guess is the other windows installation) to allow access to everything.

the reinstall “worked” in that the files copied, but now I just get a blank screen with a cursor and nothing else, no hard drive activity.

please help, thanks.