What do these HD errors mean?

[Arcady Genkin <a.genkin@utoronto.ca>]

Feb  9 13:27:45 tea kernel: hdc: dma_intr: error=0x40 { \
   UncorrectableError }, LBAsect=26406865, sector=25038000
Feb  9 13:27:45 tea kernel: end_request: I/O error, dev 16:04 (hdc), \
   sector 25038000 
Feb  9 13:27:50 tea kernel: hdc: dma_intr: status=0x51 { DriveReady \
   SeekComplete Error } 
Feb  9 13:27:50 tea kernel: hdc: dma_intr: error=0x40 { \
   UncorrectableError }, LBAsect=26406852, sector=25037984 
Feb  9 13:27:50 tea kernel: end_request: I/O error, dev 16:04 (hdc), \
   sector 25037984 

And so forth. The drive is an IBM 13G DeskStar (?) with 2M cache. The
kernel is 2.2.14. Thanks!
-- 
Arcady Genkin                                 http://www.thpoon.com
Nostalgia isn't what it used to be.