debian 4.0 hard drive problem

[lists at barrettpianos.co.uk]

All,

Not found anything on this using google so am trying the list.

The debian box has 1 hard drive.  Can't remember what I did with 
the partitions during the install.

System appears to be working but every few minutes I get the 
following error:

hdb: status error: status=0xd8 Busy ide failed opcode was unknown 
hdb: DNA disabled 
hdb: ATAPI resetcomplete
hdb: request sense failure status =0x51  Drive Ready Seek 
Complete error
hdb: request sense failure error=0x04 Aborted Command

I thought that hdb would be a second drive but as I only have 1 in 
the machine seems strange.

Also, sounds rather drastic but still seems to boot and work if the 
errors are ignored.

No other os on the machine.

Any ideas?

Keith