Sean,
I need to get a little bit more information before we can correctly identify what's going on. Here are some questions/suggestions:
1. What have you done so far? The UMI error message link that's there will pull up about 10 technotes. Have you run through any of these?
2. Are there any other backups of that server that are occurring at the same time? Is SharePoint doing any dumps or maintenance at that time of the backup?
3. Does this happen immediately at the beginning of thebackup, or does it start backing up some of teh SharePoint server and then fail? If it does backup some of the server, is it backing up some of the actual database or some of the files on the filesystem...in other words where exactly is it failing and is that consistent?
4. Is there a firewall in place between the two subnets, and if so, have you opened up all necessary ports to do backups? Please refer to the following technote for what ports are needed:
http://support.veritas.com/docs/285830
5. Try the following technote:
http://support.veritas.com/docs/284155
6. Try the following technote (depending again where exactly the job is failing. If it's during the database, see if it helps):
http://support.veritas.com/docs/255814
Please let us know if this helps to resolve your issue.
Thanks.