Backup Exec 8.6 Slow Throughput on C: drive

I am running a Windows 2000 Server (SP3) with Exchange. Everything
seems to backup normally except for the local c: drive. I get a very
low throughput of 4 MB/MIN. I have defrgamneted the drive, but get the
same results. Here is an excerpt of the job log:

OFO: Started for device: "C:"


Media Name: "Media created 6/21/2003 05:00:09 PM"
Backup of "C: "
Backup set #3 on storage media #1
Backup set description: "FSS_OFO_W_C"
Backup Type: FULL - Back Up Files - Reset Archive Bit
Backup started on 6/21/2003 at 9:12:03 PM.

Backup completed on 6/22/2003 at 9:40:42 AM.
Backed up 914036 files in 1161 directories.
Processed 3,154,291,342 bytes in 12 hours, 28 minutes, and 39
seconds.
Throughput rate: 4.0 MB/min

As you can see, it takes 12 1/2 hours to backup 3.1 GB

Any help would be apprectiated.

Thanks,
Brian