I am also having problems with Avast Free 10.3.2225 update clashing with Microsoft Office 2003.
The mouse right click menu now no longer works in Outlook, I haven't noticed if I am also suffering from some of the other mentioned issues.
I confirmed the problem is definitely with Avast Free 10.3.2225 update, because I restored the PC to before this Avast update then Office 2003 was OK again, but as soon as the Avast update 10.3.2225 was re-installed the problem came back.
I am using Windows 7 SP1 and Microsoft Firewall. What is the solution to get Office working normally again?