"Check for updates" behind a proxy server

"Check for Updates" seems to fail for me (I'm sitting behind a proxy server, which is configured in the "Updates" section of preferences). With logging turn up to Debug 2, all that appears is the following single line;
Any idea of what's wrong?

Can you try that with 4.1 and post full error message?

Well, there's a bit more there to go on;

* 2008-03-25 10:37:49.250 (ExtException) Error checking for application updates.
* 2008-03-25 10:37:49.250 Received response 400 Bad Request from proxy.******.com

Greg

OK, maybe you are using HTTP proxy that WinSCP does not support.

Quite possible, though the same proxy works fine with IE and Firefox. What standards does WinSCP expect to use; I'll do some digging.

Greg wrote:

Quite possible, though the same proxy works fine with IE and Firefox. What standards does WinSCP expect to use; I'll do some digging.

For updated WinSCP supports, only simple HTTP-based proxy.