Disk problems with Slackware 14.1 and WD EIDE drives

I have two computers with WD IDE drives running Slackware 14.1. Both of 
them have been giving me the same set of error messages which don't make 
any sense to me. Can anyone tell me what is going on with them?

Dec 28 10:53:59 workdesk kernel: [91574.369664] ata1.00: configured for 
UDMA/100
Dec 28 10:53:59 workdesk kernel: [91574.369690] sd 2:0:0:0: [sda] 
Unhandled sense code
Dec 28 10:53:59 workdesk kernel: [91574.369694] sd 2:0:0:0: [sda]
Dec 28 10:53:59 workdesk kernel: [91574.369700] sd 2:0:0:0: [sda]
Dec 28 10:53:59 workdesk kernel: [91574.369709]         72 03 11 04 00 
00 00 0c 00 0a 80 00 00 00 00 00
Dec 28 10:53:59 workdesk kernel: [91574.369720]         00 11 3c bf
Dec 28 10:53:59 workdesk kernel: [91574.369725] sd 2:0:0:0: [sda]
Dec 28 10:53:59 workdesk kernel: [91574.369731] sd 2:0:0:0: [sda] CDB:
Dec 28 10:53:59 workdesk kernel: [91574.369767] ata1: EH complete


The disk specs are

Model Family:     Western Digital Caviar Blue EIDE
Device Model:     WDC WD3200AAJB-00WGA0

The most troublesome is running the huge kernel on a Pentium 4. (Dell 
Optiplex GX240). Most of the resulting file system errors show up in 
sda2, which is the /usr partition. Several applications are no longer 
functional, so it appears to be losing active sectors to this error.

My biggest question is why is there an unhandled code? Shouldn't this 
kernel know how to handle all of the status codes the disk can generate?

Thank you,

Bob McConnell
N2SPP