I can't seem to replicate this in MS Word 2010 32-bit either and have never come across this issue myself...
Can you confirm what version of MS Office you are using please?
Have you tried Repairing your MS Office installation?
If that does not work, perhaps try updating to MS Office 2010 SP1; assuming that's what you are using (if not, MS Office 2007 is at SP2 and MS Office 2003 is at SP3 currently). Make sure you download the right version of the update for the version of MS Office 2010 that is installed on your system; i.e. 32-bit or 64-bit (go to File>Help to display the Version details). Download links for both versions are on this page: http://support.micro....com/kb/2460049