Can you send me an email, so I can send you back a debug version of WinSCP to track the problem? Please include link back to this topic in your email. Also note in this topic that you have sent the email. Thanks.

I'm experiencing also random freezes. I can't discover what is the exact cause, so I can't reproduce. I start an upload session, queue a lot of files and let winscp work in the background. Lately when I switch back, it's non-responsive.
It's interesting, in the majority of the cases, winscp is still working in the background (uploading) so I let it work. Since I'm in trouble when I stop the upload (half files are still taken and processed by the stock agency) I wait until all the downloads are finished. To know this, I check the network activity in the win. task manager, after this End task for winscp.
The problem my rise if I minimize winscp before let it work in background.
As soon as I will know more about freezing I will post here.

I did turn on the logging option which I just discovered. So I will see what that says.

Once or twice a day (everyday), I switch to the running Winscp window and it is completely blank, frozen, nonresponsive.

I have to click the 'red X' and click OK on the dialog that pops up asking me to end the program that is not responding.

Other than that I can't report much of anything other than when I last checked the window it was fine and I had just uploaded one or more files without any problem.

This just started, I am pretty sure, after the latest update 4.3.3. Build 1340 was installed via an update from the previous version.

Is there something I can enable or look for to give some kind of indication what happened? I realize this is nothing to go on by just saying it was unresponsive.