Windows shuts down and restarts smartftp

We have recently converted from XP to Vista.

SmartFTP works well BUT... it continually shuts down and restarts.

After transferring a file from remote to server and returning to SmartFTP it automatically shuts down and restarts?

Can anyone help?

We ahve changed everything even the time out to 5000 and useing favororite settings and changed to passive and back again.

Thank you.