Disable AVG by right clicking the icon and selecting close - i can't remember the exact wording but you see and option to close the shield or something.
If OE now opens OK you need to clear out loads of rubbish from your folders. Basically AVG is scanning all the folders every time OE opens and if you have loads of attachments (esp big pics) it can cause OE to hang as it times out whilst waiting for AVG to finish scanning. Once you have deleted all can afford to loose empty the deleted items and then File, Folder, Compact All Folders.
Reboot and OE should be OK whilst AVG is running. Just remember that you need to make sure you don't build up loads of old mail in your OE.
remarkably common problem with AVG and OE.