Backup issue with BackupExec 12 and MD3000i storage location.

Good afternoon everybody,

We recently added a MD3000i to use for Backup to Disk storage.  It's on its own network using two Dell PowerConnects and our backup server.  Our backup server is a PE1950 running Windows 2003 Standard Server with Service pack 2 and Symantec's Backup Exec 12.  We created two RAID5 sets and setup the two 5.5TB partitions on the server.  Initially we were having no issues we could backup to either one of the partitions.  However I found that when I moved the Exchange Backup (which is using the GRT option) from the first partition to the second it would fail.  If I set it back to use the first is would work just fine again.  All the other jobs that involve just a regular backup to disk file and are not using GRT work just fine on either of the partitions.  I've been working with the symantec guys for a few weeks now but we've pretty much come up empty except for one thing.  When we ran ProcMon from the Sysinternals suite I saw that when any file activity happens on the first partition (drive k:) it would say that process x is doing x on K:\filename.  But when I would copy I file to the second partition (drive L:) is would say that Process x is doing x on C:\Windows\system32\shell32.dll.  So say I copied a 2 Gig file over to the L drive, ProcMon will show a whole bunch File operations involving C:\windows\system32\shell32.dll.

Any ideas on why windows might be seeing the second partition differently than the first? 

Thanks.