Please go to Add/remove programs (Windows XP) or Programs and Features (Windows Vista and 7) and select McAfee product and remove Site Advisor and restart the computer
Go to www.SiteAdvsior.com and click on Free Download button and re-install Site Advisor and let me know if that solved your issue or not. Best of luck
Silly me - I neglected to mention this is on a Mac, not a PC, so it's Snow Leopard OS, not Windows. Any ideas now? Thanks!
Moved to VirusScan Other for better attention.