Email font size in body changes randomly after the message is sent

Hi All,

We're having a problem with about 10 of our users (that have reported it)
were by their email font size in body changes randomly after the message is
sent.

The message looks fine to the user as they are typing it and only notices
the font size change when someone replies to them or they go into their sent
items (or both).

In troubleshooting the problem:

* we've disabled non-essentials add-ins,
*made sure the affected users weren’t using Word as their default email
editor,
*changed their default email formatting from HTML to Rich Text

but none of these made a difference.

We're using:
Outlook 2003 SP1
Windows XP Pro SP2

Add-ins not disabled:
Advance EAS extension (Email Archiving Solution)
Hummingbird DM email integration (Document Management)
Microsoft Outlook DM extension (Document Management)

Any help will be greatly appreciated!

Evan