Google seems to show that there is no publically available firmware updates for Maxtor disks.
There are for some but only if you irritate the tech support people.
hours at high cpu usage.... There were maybe a a dozen DriveReady
SeekComplete Timeout errors clustered a few minutes apart.
That suggests the drive is having problems occassionally and that the DMA
path code then blows up when they occur.
Is there a way of viewing the contents of he command queue on
the hard drive, to see if the command actually made it across?
queue ? You are overestimating IDE ;)