X11-forwarding works with bash(linux) ut not with Putty(windows)

Hi

I have a Fedora Core 6 workstation with OpenSSH installed. I can login
to it with both with windows- and linux-boxes. My problem is when I try
to use Putty with X11-forward. There is no problem when logging in
remotely from another linux-box, and I can start all GUI-apps. But when
trying to do the same with putty from a windows-box(with X11-forward
turned on), I only get this error:

$ xclock
X connection to localhost:10.0 broken (explicit kill or server
shutdown).

Are there anyone who knows if there are anys way to fix this?

.