hierarchy of key combinations for "unsticking" a mac

1. apple - . (that’s a period) (tries to halt the current process: good for when the Mac is asking you to insert a removable disk that’s not available any more)
2. apple — Q (tries to Quit the current application)
3. apple — option — Q (a harsher version of the above)
4. apple — option —esc (tries to bring up the "Force Quit" dialog box)
5. shift — apple — Power Key (for Blue G3s & Graphite G4s)
   or,

   control — apple — Power Key (for Beige Macs) (tries to "cold restart" the Mac)

6. If none of the above work, you must unplug the power cord from the back of the machine.