I am running Windows 8 Consumer Preview x64 as the built in admin account.
However, I wanted to run metro apps, and to do that I did something in the registry I cannot remember, but it involved setting some value that included "Administrator" from 0 to 1.
Foolish as I was, I didn't realize that that probably made the admin account a normal admin account (not built-in). This is what i SUSPECT, since I used to be able to move i.e. C:\Program Files\ folders without prompts. This bothered me, so I tried to change the advanced security settings for the account. (Right click the C:\ drive and selecting the Security tab.)
Somewhere here, I managed to remove my admin rights. Now I can not perform any admin-related action, which makes it impossible (?) to correct my mistake (I can't even open an elevated command prompt.) Sometimes there pops up a window saying "You do not have sufficient privileges" or something like that.
To make changes, need to be Admin, but I screwed up the admin account. What to do?