double restart? shutdown?

I'm running OS 10.4.2 Tiger on a mini, and I have 2 restarts and 2 shutdowns in my apple menu? whats causing that?

also i have black blocks that are around various parts of my screen or icons at unknowning times.

any help would be great, i'm new to Macs.

Thanks.

I am not exactly sure what causes this problem, yet it happen the other day to an emac at work. I ran onyx (if you don't have it you can find it on versiontracker.com) and used the automation tab and repaired permissions and cleaned out all of the caches, and everything was fine afterwards.