Auto update not successful due to some problem

I currently have a red X on Sophos Antivirus. A "mouse over" shows "sophos protection update has failed". Right clicking and selecting "Update Now" causes a window to show that states "Downloading Package 1 of 4…2 of 4…3 of 4…4 of 4" then it shows "Installing Package 1 of 1" then it just quits. A look at the log file shows:
Installation of RMSNT skipped
Installing Product SAVXP
The manifest file for product SAVXP was invalid
Installation of Sophos Client Firewall skipped
Installation of Sophos AutoUpdate skipped
AutoUpdate finished
If I repeat the "Update Now", the same thing happens again. Rebooting does not help. Any ideas?
