Hi Smashing -
You can try running the VSSADMIN LIST WRITERS command from the command prompt to see if they are stable.
I suggest you go into the Job Properties of the job your experiencing this issue with.
- Click on the Job Setup tab
- Right click the job that you are having the issue with and click properties
- Click on the "Advanced" option
- Change the setting "Open file backup when Advanced Open File Option is not used" to "Never" instead of the default "With a Lock"
- Re-run the backup job to test.
I hope this helps!
- Jared