This has been fixed by Greg's Buttons version 3.2 and above.
Greg's Buttons 3.0 has a feature that allows you to fill alerts and dialog boxes with color. Unfortunately this feature conflicts with the Find/Change dialog in ClarisWorks 1.0 and 2.0. Find/Change may appear to work at first but after closing the Find/Change window any attempt to access it again will fail.
Workaround:
Just turn off the Colorize Alerts and Dialog boxes feature or exclude ClarisWorks with the Exclude button.