2.6.29 seems to be the most unstable kernel series for quite a while, at least for me. First Intel SSD disks weren't detected on Nvidia chipsets. Then the whole kernel freezes (hard reboot needed) during heavy NFS load when used as a NFS server. ALSA sometimes fails to init the HDMI audio output. The forcedeth driver put the NIC in some weird hard offline mode on module unload, which even survives a power cycle. Even BIOS think that no cable is connected... I have to temporarily boot XP and press reset when the nic lights go green again to be able to netboot with gPXE. Right now I'm running 2.6.30-rc4 and it already seems much more stable than 2.6.29. ever were.