Is your Mac OS X server crashing frequently? If so, we have two questions for you:
Question 1: Do the crashes, restarts, or slow downs occur primarily when several people are searching server volumes over the network?
Question 2: Are you running Mac OS X Server 10.4.7 or later?
If you answered yes to both these questions, you may be suffering from a problem that exists in Mac OS X Server 10.4.7 and above where multiple Spotlight searches can render a server unresponsive.