ata3 and ata4 disk errors

[JD]

I am getting lots of ata3 and ata4 errors in the system log.
In spite of these errors, when I unmount the partitions of both drives
and I fsck every partition, no errors are found.
The out of dmesg with the errors is at
http://www.sendspace.com/file/761te2

The drives are esata-2 (300mbits/s) and are housed in brand new external 
enclosures
with 80mm fans, connected to the laptop via a 32-bit cardbus with 2 
esata-2 ports.

The drives themselves are not new. One of them is 6 years old, the other 
4 years old.
Their former enclosures, which were also equipped with 80mm fans, were 
discarded due
to their power supply failures.
Hoping a hard drive expert could tell me if the errors are caused by the 
cardbus adapter
or the hard drives themselves.