Aboard a cargo ship: 2 Win7 machines, one at Captain, one at Chief Engineer. Systems both new HP boxes about 6 mo. old with Win7 Pro, Office 2007. Systems see each other on a wired net but Captain is the only one allowed to send email. Emails are sent via Inmarsat satellite radio connection, and served via marsatmail.com. Problem now is that no email can be sent with any binary attachment and have the attachment survive the trip; attaching PDFs, JPGs, any other non-text attachment always results in "invalid image" or "insufficient data for PDF" errors on the receiving end. Captain came down with this problem after 3-4 months of proper operation; subsequently, he swapped out his machine with Ch. Eng. machine which then once again allowed him proper operation sending email with attachments. However, after only a few weeks, this machine again reverted to the same failure, i.e. all binary attachments end up corrupted. I was called onboard to fix what owner perceived as a virus problem. However, after many hours of scanning with MWB, MSE, AVG, Combo Fix, in Safe Mode, clean boots, brand new user account, as well as installing Thunderbird to test with rather than Outlook, results are always same... all binary attachments are corrupt. They use a couple of flash drives to move files around aboard ship, however, scans on those drives produced no results of virus infections. In short, there was not ever a single indication of any virus being active; no suspicious popup screens, no unusual entries in any of the Runs, no virus scan hits *at all*. So, I left after many hours, thinking the problem must be elsewhere, perhaps at the server end. I advised owner to create a new mailbox account and then re-test but now we find that too produces the same result. Also, we're unable to find any other users at marsatmail.com with the same problem. The systems use a compression program, MVS Fly Carrier, to interface with the transmission system. I'm wondering now about this software being the culprit; unfortunately I didn't attempt uninstall/reinstall of it while aboard, as I was convinced the problem was elsewhere. I have submitted a request to that company as well. Truly flummoxing. Any clues?