Your latest attachment is 55,175 bytes, a few thousand bytes more than on your comp! This is very weird indeed.
Like Barrie_Dude said: it looks like a kind of time-out. But your modem cannot be the problem: a bandwidth of 1 Mbps (megabits per second) is what I have also; there are higher speeds, but it should be more than fast enough.
SDRAM = Synchronous Dynamic Random-Access Memory
(I looked it up). It's the type of internal memory most computers work with today (although it's slowly being replaced by DDR, "Double Data Rate"). I think what Barrie was asking is: what other programs are you running while posting the attachment? I suppose that, if too many programs are running in the background, this might be responsible for a (too) slow transfer of data...
I'm sorry, Californication, I can't come up with any other explanation.
But I can suggest a solution, albeit not a very satisfying one.
If you're only having trouble attaching bigger pictures, make them smaller first. There are different programs you could use to do that, but beware: some programs may store your smaller pic using more bytes! (Microsoft Photo Editor does that - I guess it stores it's jpg's with a not very efficient compression.)
(If you have a recent version of the basic Paint-program, one that can store files in jpg-format, you could use that. Open your Pic.jpg in Paint, press ctrl+e and reduce the height and width values proportionally - then save the resulting pic under a new name.)
Try to attach the smaller file.
If it still comes out warped, you could again reduce it...till you get an intact one. After some experimenting, you may find out how many bytes your attachments may have without being damaged...
I know: it's not really a solution.