Is it suspicious or infected?
Can you post a screenshot of the error message?
Can you send the samples to virus@avast.com ?
You can zip and password the files... Inform a link to this thread and the password used.
You can send the files to Chest and, from there, resend to Alwil for analysis.
Thanks.
You can use Alwil FTP server as a second way to transfer only big files. Upload them to
ftp://ftp.avast.com/incoming (please, note that you won't have READ access to the ftp server, just write - so you won't even be able to see what you've just uploaded).
Note that uploading the files to FTP, without additional contact, is not a good idea. The FTP is not monitored - so unless they're expecting some files, they won't really see them.