It's been about a year since someone posted exactly the same thing...
There's a removal tool on that first page.
I am having the exact same problem on windows vista - I don't have any other anti virus software installed, I have never used anything from at&t, I have tried the uninstall program listed above 5 times and even downloaded other uninstall software to no availe - what's wrong???
I've altered your user name to conceal your email address for security reasons. You will have to log in again as mdnightsky.
I'm lost for any further explanations I'm afraid. This is an old thread and I only found the previous things from a web search.
Perhaps you should contact Technical Support Chat via Useful Links at the top of this page.