ATA related lockup in 5.2-RELEASE

I am getting some weird freezes with 5.2-RELEASE.  I think they are 
related to the ATA driver.  I have a Promise Ultra 100/TX2.  I am using 
the cable that came with my disk so I assume it is correct.

My system boots all right to an IDE disk.  If I try moving a file 
bigger than 1.5 megs or so onto the ATA drive, the system completely 
locks up.  Small (e.g. 30k) files can be moved onto the ATA drive and 
read with 'more'.

I am more than happy to run tests to help diagnose this issue, but I am 
not seeing anything unusual in the log files; it's a total instant 
freeze (sometimes a spontaneous reboot).

Scott