MS outlook 2007

Hello Just recently I have been having problems with AVAST4.8 sending e-mails…i have to disable it in order to send mail…it never done that before

As avast! has been delivering its V5 version since January 19th, 2010 It would be best to update to V5:
http://blog.avast.com/2010/01/19/avast-version-5-0-is-here

Aside from the obvious updating to avast5, which for me is a better option all together.

What errors are you getting ?

Make sure the avast plug-in/add-in is not disabled in MS Outlook:
Outlook 2007 > Tools > Trust center > Add-ins > Manage Disabled items.