I'm not a product expert but I have moved your post to the VirusScan area. Hopefully someone can help you soon.
Please give the exact error that you got when you tried the update
Here are the last few lines that I see when doing the update.
Update failed to version 5929.0000
The updates fail due to a lot of reasons.
Lack of internet connectivity can be one for starters. It also happnes when the download package gets corrupted in the process. I suggest you try and run the update now again and let me know what happens.