Since Tiger, I have repaired permissions, run fsck -fy and the Mac Janitor once a week. STILL I have Acrobat 7, Indesign CS, Preview and the odd browser (Safari, Firefox) "Unexpectedly quit" with the option to Reopen, Close or Cancel happen to me at least once a day.
A system with 2.5Gb of RAM and 2x2Ghz G5 processors would run better than this, had I have had a guess, but experience has proven otherwise.
Waiting for 10.4.2 to see if ths BS clears up.