The problem is that when your Dock freezes in OS X it can be difficult to get to programs to restart it or anything pretty much. Luckily, when mine froze today I had a Term open and this is how I restarted it without having to power down my damn computer.
jstump@Joseph-Stumps-Computer
jstump$ ps auxw | grep Dock
jstump 3231 0.0 0.5 169272 4204 ?? S 9:48AM
0:04.75 /System/Library/CoreServices/Dock.app/Contents/MacOS/Dock -psn_0
jstump 6868 0.0 0.0 18644 92 std R+ 11:45AM
0:00.00 grep Dock
jstump@Joseph-Stumps-Computer
jstump$ kill -HUP 3231
The second field in ps‘s output is the pid for that process (Process ID). Using kill we can restart the Dock without crashing everything. You’ll see your Dock disappear for a second and reappear in working form a second later.
Instead of messing around with ps, you can just do:
$ killa -HUP `pidof Dock`
Or, better yet:
$ killall -HUP Dock
Er, the first command should be:
$ kill -HUP `pidof Dock`
Even better yet – killall Dock
–Paul