For those who haven't seen my several previous postings about problems with this (now not quite so) new PC, I have an ASUS P5N32-SLI Deluxe motherboard. The boot drive and primary filesystems are on an SATA disk and I'm having no problem with that. However, I recently plugged in a couple of IDE drives salvaged from my old PCs and I'm running into trouble with one of those. The drive in question is a 20GB Maxtor 92049U6. It had an old RH5.2 ext2 filesystem on it when I first plugged it in, from which I tried to recover some data to back up to CD. Mostly this worked, but I started encountering read errors accessing some files so I unmounted the partition and started a fsck on it. At some point during the fsck (I was off doing something else on another workspace at the time), the system locked up hard, leaving the disk activity LED lit. I had to reset the PC. So at that point I booted single-user and ran the fsck from there. It completed successfully after fixing a number of problems. I continued into multi-user mode, finished doing my backups, repartitioned the drive, and started "mkfs -t ext3 -c" on the larger partition, to check for bad blocks. Again at some point part way through the mkfs, the system locked up. Back to single user mode, run the "mkfs", everything finishes fine. Back to multi-user mode, start to copy some large files onto the drive. MD5 sums fail to match for some of the copied files. Unmounted and started up "fsck -y". This succeeded, after fixing a number of errors, so (at this point just as a test case) I re-copied the files with bad MD5s. Some of these came through OK this time, others still did not. I decided perhaps this meant there were still bad blocks on the drive that a read-only test was not finding. You'd think I'd have learned, but encouraged by the success of the previous fsck I optimistically started up another "fsck -c -c -y" on the suspect partition, and this time I waited around to watch it. About 1.6GB into the 16GB partition, the system locked up again. This time I booted into a hard disk diagnostic program instead of into CentOS. After running overnight last night, a non-destructive read-write surface-scan reported no problems with the drive. This leads me to suspect that the problem is with linux, but I don't know how to proceed with diagnosing it. Suggestions would be appreciated.