When I try to upload a file (Specifically .doc is all I have tested) at the moment. It only happens when I use the current upload system, when I use the ‘old uploader’ it works fine.
The error message says that the firewall/anti virus may be blocking the upload.
avast free is an antivirus only and does not block anything, just scan. Even less, uploaded files.
Which is your firewall?
Is the file being used by MS Word, i.e., is the file closed or open in MS Word?