Is this on a fresh installation or did this just suddenly appear on an installation that has been working?
What Operating System (OS) are you using? (XP Home, XP Pro, Vista Home/Bus..., Windows 7 Home/Pro/Ultimate) Also, is it a 32bit OS or 64bit?
Which Mozy are you using? (MozyHome Free/Paid, MozyPro) What version of Mozy are you using? (2.x.x.x)
What anti-virus/firewall tool are you using?
Have you had problems with your system clock (the date/time)? Maybe the RTC battery is dead.
Sig::: Practice restoring a file before you need a file in an emergency. Using MozyHome (free) 126.96.36.1998 on W7 Pro 64bit http://mozy.com/home/download (file and release notes) http://mozy.com/pro/download (file and release notes)