When I try to view an attachment in my e-mail I get the following message " the anti-virus has reported an error, cannot scan this object for viruses"

Is this generated by Clamwin?

what email client and how do you get the error - message dialog or is it embedded in the email?

I am using The Bat which has a Clamwin add-on.
The message is in a dialog box generated by The Bat

Here is the log
04-05-2007, 09:08:49: ANTIVIRUS - Examining the attached file for viruses before saving to disk as "C:\Proposals\Lucky_Friday\Shaft Design Work - Hecla Lucky Friday.eml"
!04-05-2007, 09:08:54: ANTIVIRUS - The anti-virus has reported an error, the object cannot be checked for viruses

That name sounds suspicious. Don't try to open it. Just upload the file to VirusTotal to scan with multiple AV scanners and see what they report. If it turns out to be malware, delete it from your computer. VirusTotal will send a copy to all the scanners involved that failed to detect it.

Regards,

The file is fine, its actually an e-mail I forwarded from another application.
I changed the filter in Clamwin to ignore *.eml but this may only apply to file scans, not e-mail attachments.