Since I upgraded my Debian testing system recently, and received version 5.0.24-1 of the mysql-server package, slimserver refuses to start. Looking in slimserver.log, the culprit appears to be:

060822 20:51:55 [ERROR] Error message file '/usr/share/slimserver/MySQL/errmsg.sys' had only 463 error messages, but it should contain at least 466 error messages.
Check that the above file is the right version for this program!
060822 20:51:55 [ERROR] Aborting

... it seems that your package is a bit too closely tied to the version of mysql-server that is installed. Until this is fixed, it looks like it needs a dependency on the specific version of mysql-server tht the errmsg.sys file matches.

FWIW I worked around it by putting the following in /etc/apt/preferences:
Package: mysql-server-5.0
Pin: version 5.0.22
Pin-Priority: 1001