Disc images and DVD's fail to mount

OK - has anyone else had this problem? It happens to me all the friggin time and has been for a few months now. Easily reproducible too:

1. Select 'Restart' from Apple menu
2. Restart hangs (every single time regardless of whether any apps are running or not)
3. Force restart via power button (every single time)
4. CD's/DVD's/.dmg fail to mount (every single time)
5. Repair permissions (every single time)
6. Restart (see #2)
7. Zap PRAM 3x (every single time)
8. CD's/DVD's/.dmg mount

I am so tired of this. I have never had this many unfixed problems with any Mac or OS, not even 7.5! How hard is it to create a computer that restarts properly? And why oh why does it refuse to mount my media?

Oh - #9 new symptom: DVD mounts; eject DVD; insert new or same DVD; DVD fails to mount.