IDE or SATA? I had some serious issues with kubuntu a while back. It was a SATA hard disk, 10K RPM, and I could get through the whole installation and configuration part of the install, even get to the KDE desktop, but as soon as I started installing security updates, it crashed. Every single time, randomly during the install process.
Try running ext4 on SSD. I’ve never been so comfortable about a hard disk as I was with my 100 GB SSD. It ran smooth as silk, no data access issues, quiet, and I consistently got 1+ GB transfer rates (between 2 SSDs).
For the record, I would not recommend ext4 in enterprise environments. Linux runs amazingly well on a ProLiant DL360, but I can swear that ext3 ran better on a RAID5 disk array.
I don't remember the details of the stability problem, other than having to reinstall Xubuntu 9.10 several times before I gave up and went to 9.04, which has been quite solid. Was sure glad I had /home in its own partition!
I used Kubuntu for several years, but it became progressively more sluggish with newer releases. Xubuntu 9.04 is not exactly snappy either on this hardware, but responds quickly enough.