OpenSUSE :: Single-card Multiseat: Xephyr Freezes?

I have a multiseat installation consisting of a single graphics card controlling two screens, with one Xephyr instance on each. Each one has its corresponding mouse and keyboard assigned via appropriate command line switches--evdev is used as the input device driver.

  Since a recent "zypper update" (about two weeks ago), this configuration has been having problems: as long as the keyboard and mouse are not being used, it runs fine (e.g., over the weekend when it just sits on the KDM login screen), but when it is being actively used, the Xephyr process will eventually end up in a hard lock-up requiring a kill -9. A lock-up of one Xephyr screen does not seem to affect the other, although both will end up frozen eventually--sometimes this takes only a couple of minutes after the user starts his activity, and sometimes it may work for half an hour or so before it gives up the ghost.

There are no relevant log entries anywhere I could find, and neither is anything reported on Xephyr's stderr/stdout. I have tried downgrading to an older version of Xephyr, as well as compiling xorg-x11-server-extra locally from source, with no success. Only thing I can think of is downgrading to the previous kernel. Unlike my Debian machines though, OpenSUSE does not seem to keep the last few previous kernels for you to boot into in case of problems, and I can't see how to downgrade kernel via Yast2.