i know yr think this may be daft but you have said which norton you have, its just helps more in knowing what you have please. anyway i fine http://www.symantec.com/techsupp/support_options.html which in norton support and help
also i find this hope its ok to post this one
http://www.tek-tips.com/threadminder.cfm?pid=742&page=1 its for norton fourm they might be someone who had same problem
the more we know what its doing and when it started and what version you have the better we can hope you, have u installed any new programme's at the time it happened?
you havn't changed anything in properties on yr screen where you can change yr font from normal to ex- large
this is for your outlook e-mail, when clicking internet explorer once u opened it
in there check yr size of text, u do this you got to view on task bar click on view then go down to text size, and see what size it set at that could be causing your large font in e-mail
i also find this in norton which gives you help on font problems, let us know how you getting on with this
How to change the default font style and size for a Cover Page
[size=-1]Situation:[/size]
You want to know how to change the default font style or size used in a cover page. When you change the settings in the preview or annotation screen, the settings are not saved.
[font=ARIAL,MS SANS SERIF,UNIVERS,HELVETICA][size=-1]Solution:[/size][/font]
You cannot change the default settings for the cover page in the preview or annotation screens. This must be done in Cover Page Designer.
In Message Manager, click Go, and click Cover Pages.
Double-click the cover page you wish to modify. The cover page will be opened in the Cover Page Designer.
Click the Fill Box on the cover page to select it. When selected, the fill box will have handles on the edges and corners.
Change the font type and size on the toolbar at the top.
Click File, and click Save to save the changes.
Close the Cover Page Designer.
NOTE: The Quick Cover page font style and size cannot be modified.
this may help but if you go to norton site they have a help part which could also help