Ghost 12: Device \\.\SymantecSnapshot0 cannot read 12928 sectors starting at LBA 371 090 592

I'm getting this same error message whenever I try to backup my system drive :

 

Ghost 12: Device \\.\SymantecSnapshot0 cannot read 12928 sectors starting at LBA 371 090 592.

 

Everything worked just fine last April when I last created a backup (this is my mother's computer).

Now I'm getting this error whatever drive I specify as target. I tried three different hard drives, both internal and external : same error.

(numbers shown may vary though).  

 

This occurs right when the backup operation first begins to write into the the "Norton Backups" directory, after gathering the data.

The hard drives themselves are just fine. Some where NTFS, some FAT32.

I'm not sure what Ghost is using to access them, but this looks very much like something is broken.

It appears unable to access any drive.

 

Oddly, the documents backup works ok.

 

 

End error is : Error e7c3000f during Computer Backup operation execution

 

 

Maybe some Vista update broke a Symantec driver or library or something.

 

The computer is a brand new (a few months), little used HP computer  running Vista (Service Pack 2) and Norton Internet Security.

 

Any help greatly appreciated.