I've been troubleshooting some problematic Exchange backups. We are using Backup Exec System Recovery and it hasn't been truncating Exchange Logs. Upon further investigation, we found that Exchange doesn't think it's been backed up either. I did a vssadmin list writers, which returned several (including Exchange) in a  Waiting for Completion. I did the standard reboot/restart services with no luck. I then re-registered VSS and rebooted. Now it's a blank list and I haven't been able to get them back. Any suggestions?