Update: The Helvetica font issue is addressed by the hotfix in this article:
Description of the Word 2010 hotfix package (Word-x-none.msp)- December 14, 2010
You can also install the update from Adobe to fix the problem.
We're seeing some issues with Outlook 2010 crashing and restarting while reading messages. This may be caused by an incompatibility with the Helvetica font and Office 2010. (Word 2010 is also affected when you use this font in documents.)
Specially, only older versions of Adobe Times or Helvetica Type1 fonts cause the problem and uninstalling or updating them will fix the problem. Adobe released an update which will fix the problem with Office 2010. If you are affected by this crash, you can download the update here: http://kb2.adobe.com/cps/860/cpsid_86033.html
To uninstall the fonts, go to Control panel, Fonts and look for Helvetica fonts. Any that display odd characters instead of "Abg", delete the font as it is corrupt. If you need Helvetica, find a newer version that displays properly in the Fonts folder.
Note that this crash is specific to certain messages and/or senders and is not a common cause of crashes. It is more common if you installed older versions of software that installs fonts, such as Adobe Acrobat.
If Outlook 2010 crashes when you hit Reply or Forward, check the "deliver to" folder in Account settings, reselecting the folder.