Error message” “Anti-virus software failed unexpectedly while scanning this file” and yet you are able to download the file in IE and Firefox, the solution below may just solve the problem. The dumb Microsoft Support website just offer loads of useless advice.
Rename c:\program files\AVG\AVG10\avgoff2kx.dll to avgoff2kx.bak
Close Google Chrome program and reopen again and the problem is resolved.
The best discussion thread on this topic can be found here.