Incremental Fails

Acronis True Image 8 build 786
(serial number available upon support request) - Removed by LowWaterMark
XP with SP2
Dell 8100

I recently purchase True Image 8 via download, and installed with no
problem. I also created a backup image of my three hd partitions with
no problem. I have also run the verification to make sure the image is
correct. I have seperately backed up the main C: drive for extra
security. All the backups are going to a new USB connected hard disk,
a WD 200G Caviar EIDE drive. I have checked all the drives with check
disk to be sure they are okay.

My problem is that whenever I try to do an incremental back up it
fails with a write error. The most recent attempt resulted in the
following errors:
---
Error 7 (0x70004) Failed to write data to the image archive file. A
possible reason might be poor media quality.|: None
{message is repeated as Information rather than error}

Error 1 502 (0x101F6)Operation with partition "F:" was terminated
with code 4 "Write error"