user access control (uac) limits application software to standard user privilege. This is good as, for one thing, it helps prevent malware from get greater control without user authorization. there have been some complaints about uac. i keep it on for my users, as they have a habit of getting into trouble. for my own computer, i turn it off because, hey, i like risky computing.
Windows 7 uac is a lot less of a pain in the butt then was vista. so, you may wish to reinstall sw with uac. here's some additional information.