Word 2007 “Find” Unstable

I have a problem with Word 2007 that puzzles me. When I activate “Find” (e.g. Ctrl+F) with the sample file (no longer online), Word stops responding and needs to be killed via the Task Manager. My configuration is as follows: Windows XP ver. 5.1 (build 2600.xpsp_sp2_gdr.00814-1233 : Service Pack 2). Microsoft Offfice Word 2007 (12.0.6311.5000) [...]