Gmail, document contains no data, why do I get this when I try to send attachments?

the title says it all, with Gmail I some times get the “document contains no data” error inspite of the fact that the document most definitly does contain data. I have even tried to change the file extension to bypass any weird filters but no luck. it gets damn old trying to send files over the net and finding out I cant.

in a related question, why do I get the “operation has timed out when trying to contact the hampsters at the SD message boards” message when I try to post on my way out the door?