NIS - System At Risk Message

Hi.  Yesterday my NIS 2011 notified me that my system was at risk, so I clicked the Fix Now button and it went through the Live Update process.  After getting some updates and finishing, I clicked Ok and the screen under that then said Protection Updates Not Fixed.  Since then I've gone through the same process several times with the same results.  I don't know what other steps to take to fix the system since Fix Now only leads to Live Update.  I've used Norton Utilities to run Registry and Disk Cleaner/Defrag just in case, but no difference.  (The only other oddball thing maybe worth mentioning is that this morning one of my favorites was causing an expired certificate dialog to pop up when I opened my favorites list, but when I deleted it, it went away... and it wasn't doing it yesterday when the At Risk problem started, so probably not related.)  I have a Windows XP platform and am running Firefox 3.6.15.  Any help would be appreciated, thanks.