Do you have keepalives enabled or disabled? What if you set it otherwise?

I am connected and authenticated fine. File transfers are fine. However if I leave window alone for a few minutes, it shows the error...

"Network Error: Software caused connection abort"

Now, I never had this problem with winscp376, xppro...however, not that I got a new pc with vista, and installed the latest winscp version, this has happened every day...

It has nothing to do with firewall (hardware or software) as none of that has changed. An ideas?