I've had the same problem as cptigloo_2000 has. Whenever I deleted an email, Outlook crashed and reloaded. I've read the support of avast! homepage and tried to 'deactivate' the MSN Toolbar. But nothing was to help except to delete the instalation of it.
Well, I asked myself, why using MSN Toolbar, if you want to have a popup-blocker only. So, I tried to install the google one... but instalation crashed with an error message and stopped.
I don't have an idea, but it seems to me, that there's something about 'popup blockers' avast! doesn't like...
I don't have any popup blocker anymore, but it seems to me, I will not install one in the near future...? Because this thread is 2 weeks ago, and still not 'solved'...