Bert's advice is sound. I would NEVER uninstall then reinstall AC on the server because that should never be a solution to any problem. It's your entire practice that's on the line. If it were Java or Adobe I wouldn't think twice about it. That being said those programs just work...they never break. Their upgrades don't require 4 hours on a weekend to complete. Their upgrades are simple patches that install in 30 seconds to 3 minutes. They don't require separate database tuners that aren't bundled into the upgrade software.
Installing AC is one of the more difficult programs I've ever installed. but not the hardest. The hardest is installing Small Business Server OS. That took a long time, but AC is right up there in level of difficulty.
I get the same error you are reporting on occasion. I never do anything about it, and it never bothers my back ups. I use Backup Assist v6. Sorry I can't help.
