Ok, I successfully extracted the file to another location and think I successfully sent it to the virus lab (I got some strange dialogs after I hit ‘submit’ so not completely confident it sent ok).

I have now also been able to restore my application functionality by copying the extracted file to the original location. I noticed when I did this that Windows 7 warned me I needed administrative privileges to do this (as it was going to a subfolder in ‘Program Files (x86)’ folder). I was logged in with suitable privilges and the copy worked fine, and restored my application’s functionality. Note, I was logged in using the same account (with administrative privileges) when I first reported this problem so this can’t explain why the restore didn’t initially occur - unless, of course, there is a bug in the restore function in avast that does not interface properly with Windows 7 64 bit under these circumstances.

Cheers
Glenn