Server is an HP ProLiant DL385 G5 running Server 2008 R2 64-bit on x2 Quad Core Opteron processors with 8GB RAM, and RAID-5 array. The backup software is Symantec Backup Exec 2010, using 1TB external Western Digital Essentials drives. I have tried 3 different (identical drives) and still have problems with the backup workinng properly for anywhere between 8GB - 72GB of backup, then it justs sits there. When you cancel the backup job it will take 20 minutes up to 2 hours to successfully cancel the job. Symantec software is responding during this time and only shows an error after successfully canceling the job. That error is "the driver detected a controller error on device harddisk1 dr1". I have installed a MS hotfix for USB driver issue that sounds exactly like my error, but only difference is that before I installed the hotfix I never received any errors. The only other windows log event are ESENT event: 508 performance warning. I am running Live Update again currently for Backup Exec. I am also going to run the Western Digital diagnostics against at least 2 of the drives to see what results from extended test can be found. All three of the external drives are brand new and the Symantec installation was just installed and has not worked yet.