I'm aware of the problem. Hope to fix it in future. You may switch to "temporary directory" mode of drag&drop. It should work on Win64.
I am running WinSCP on XP Pro 64bit and it for the most part works great running
in 32bit mode. However if you try and drag and drop from WinSCP to the desktop it does not work. You get the following error:
"WinSCP was not able to detect folder, where the dragged file(s) was dropped...."
There is more to the message but I think that should give you the idea.
If you then click OK to this error it creates a directory where the file should have gone with a name like scp46302.
Other 32bit programs can drag and drop fine on the 64bit desktop so I think it just a minor issue to fix this.