If serial via logoedit worked before, and then suddenly stopped working with no other changes, I would suspect cabling. That's what it was when I started having trouble with my serial connection: The cable was frayed and had to be replaced. This was not immediately obvious (cable looked fine), but the replacement cable solved all problems immediately.

Other possible problems for serial uploads are other apps grabbing the serial (such as palm) or a serial IRQ shared with a modem IRQ (such as a mouse on com1 with the serial on com3, or a modem on com2 with the serial on com4).

There was one problem on certain computers where it seemed that "slowing down" Hugo's dowload.c code by making it print debug messages helped it. This only happened on one or two computers that I know about, and was always fixed by moving to another computer.

In theory, that last bug could be solved by a slowdown instruction at the right "spot" in the code. However, despite my requests, I have not yet been offered any help in testing/debugging this by someone experiencing the problem. Since I can't reproduce the bug myself, I can't code a work-around to a problem I'm not having.