In order to give you more accurate information, we need to know exactly what you're actually running. Your subject says Office 2010, but there is no Mac version of Office 2010. There's MS Office for Windows 2010, but for the Mac, there's Office 2004 (won't work on Mac OS X 10.7 or later), Office 2008 and Office 2011. The latter two should work fine in all recent Mac systems. What version do you actually have?
Also, your profile indicates that you're using Mac OS X 10.6.4 (Snow Leopard), but you're posting in the Mountain Lion (OS X 10.8) forum. If you're using Snow Leopard, you may get different answers, as Office 2004 will work for you while it won't work for Mountain Lion users.