diff -r 3f74d0d4af4c -r 740e5562c97f src/gui/text/qfont.cpp
--- a/src/gui/text/qfont.cpp	Thu Apr 08 14:19:33 2010 +0300
+++ b/src/gui/text/qfont.cpp	Fri Apr 16 11:39:52 2010 +0300
@@ -2612,8 +2612,10 @@
     } QT_CATCH (const std::bad_alloc &) {
         // no cache - just ignore
     }
-    if (cache && cache->hasLocalData())
+    if (cache && cache->hasLocalData()) {
+        cache->localData()->clear();
         cache->setLocalData(0);
+        }
 }
 #endif // QT_NO_THREAD