Cant convert incoming mails to html in outlook 2007 if avast is running

Please help!!! Avast mail scan is not allowing HTML emails to pass through it converts it to text, only when i deactivate Avast does it allow HTML messages. I cant remember but i did change something in avast email settings. Can you please help me and tell me what to do or correct.

Mark Farrell-Watling
ITC Support/Network Security and Support
CMAINFO