Thanks for your report. I was not able to reproduce your problem.
I have sent you an email with a debug version of WinSCP to address you have used to register on this forum.

Windows 7 Enterprise - Service Pack 1
WinSCP Version 5.1.7
Transfer Protocol - SFTP
GUI Interface - Commander

I installed the programme and successfully connected to a UNIX server (Server No 1). I then tried to re-size the programme window. Horizontal resizing seemed to work, but when I re-sized vertically, the programme froze ("hourglass appeared and no components of the programme would work").

I tried this several times - tried uninstalling and re-installing and used installation EXE files from the WinSCP site and SourceForge.

Colleagues on similar machines appeared to have no problems.

As part of the trial and error testing, I then opened the programme and without re-sizing did a file transfer from the UNIX server to a local drive. After this the programme window could be re-sized without freezing.

I then closed the remote session and opened a new one on another UNIX server (Server No 2). I immediately tried to re-size the programme window and found that on a vertical re-size the programme froze. I terminated the programme and reopened it and immediately did a file transfer on Server No 2. The programme window could again be re-sized without freezing.

Now I can connect to either Server after starting the programme and can re-size the programme window immediately without doing a file transfer.

This seems to be a problem with the programme on first use after installation.