When do you get the errors?
In my case, I wanted to transfer a directory about 200 megs in size from a Windows XP to an Ubuntu 5.04 (and also to an RH FC4 server), involving about a dozen subdirectories and perhaps 200 files. It seems to error sporadically, usually after 10-20 megs have gone through the pipe.
I switched over the SCP and was able to SCP over a directory of 1.2 gigs without any problem, so it seems to be a problem with the SFTP implementation. SCP seems pretty stable, and I'll use it from now on.
I'm doing this behind my router on a home LAN. Is it possible I need to lower the speed downward from 100% or that some line noise gets into a packet and the corrupted size exceeds its allowable limit, causing the seg. fault server side? I've relied on WinSCP for years and not seen this problem before.