I have the latest suite of GPG4WIN.
When I send an encryptet mail a message with an attachment is store in the “sent” folder.
When I click on it a message like “could not open the item. The attachment is not compatible with the operation”.
I have Office 2007 32Bit
Windows 7 64Bit
Kaspersky Pure Antivirus solution
GnuPG 2.2.0 Beta (I had the same error with 2.1.0)