yup what you got there is the KP screen (kernel panic) think BSOD and your on the right track.
loads of threads dedicated to this issue, open "systems profiler" if you got the WD 160gb Hdd, that might be your problem right there, I suffered a lot from this issue. adding power options in SP "never set hdd to sleep" battery and AC mode fixed it for me, haven't had a KP since.
or a new hdd
note that was my fix and this may not work for you, >>but<< KP's are not a given on minis, and can be fixed with investigation.