Vista adminstrator problems

I'm running Vista home version. Somehow, my "guest" account got switched to administrator and my adminstrator account is now a "standard user". of course, a guest account is not a true administrator account, so I'm having all sorts of problems loading and running software (like I don't have permission to run Microsoft.net framework 3.0 in my standard user account, even though I've granted full priveleges). The problem is that I CANNOT switch the accounts back in the user accounts control panel. My (formerly) main account cannot be changed to an administrative account from either the guest (now adminstrator) controls panel or the (formerly) main account. WTF!
Then, when I try to add a new user, I get a weird message about how I can't use symbols like !< and the like in the name even though I'm typing a normal name like "Sam". Any ideas?