Sorry I updated the file now. I'll reattach it now.
Well that is a pretty legit reason why it can't be scanned, that error is actually a windows file system error, so the file is locked and avast can't unpack it to be scanned.
Error: The process cannot access the file because another process has locked a
portion of the file (33)
Note: it would have been easier just to copy and paste the text into the post rather than have to create a file and attach it and we don't have to download/open it.
So essentially I wouldn't worry about this (legit reason why it can't be scanned), but what is the scan you were doing as in a Quick or Full System (pre-defined) scans don't think this file would be scanned ?
If this happened whilst you were opening Outlook (?) then I believe there is a setting in the Mail Shield, Expert Settings, Behavior, to scan archived messages when opening. This is off by default did you change this ?