There was enough empty space on the NTFS partition I had set winscp to transfer to. WinSCP was configured with the "explorer" style interface, and was run on Windows Vista (32-bit). "Hibernation" and all such power-saving features have been disabled, excluding those that require non-interactive inactivity, such as the hard drive being powered off after 20 minutes of hard drive inactivity. It has caused no previous issues.
I have read the FAQ and seen that it states that there is no ftp file size transfer limit. It is possible that another issue is causing the restart. I cannot know for sure as I closed the window before I knew about the log.
If you would like, I can set up a similiarly configured ftpd on my LAN to test. Please let me know if this is desired. I won't upgrade or make any changes I think could affect this functionality until I get a response.