When you open a document using Adobe Acrobat Reader 5.0.6 (and maybe other versions) and type CTRL-F to find something and the string is not found, clicking OK will crash the application. Also when you're not on page one and it asks to wrap around the search, clicking OK will crash it. If started from the commandline, it will display something like Exited with error code: 0x400e0009.
The solution (or rather, workaround) is NOT to find from page 1 and when it asks to wrap around, press cancel. When the Reader is crashed, kill it with killall -9 acroread or start xkill and click on the window.