Windows Firewall problem?

Anyone heard of any sudden change in Windows Firewall (e.g. some sort of "upgrade" rollout) that has begun to block FTP connections? I uploaded some big files about a week ago, now I can't get connected to my web site with three different FTP programs - but it's working fine via my my iBook on the same network, router, etc. Needless to say I've checked the Windows firewall setup, and it SAYS the programs ought to be allowed, but they aren't. If I switch it off, I can connect.

Before anyone asks, I've only got Windows Firewall on this PC since it's behind a hardware firewall. If it was a laptop I'd have something a bit tougher on it.

Not an urgent problem, since I can use the iBook or switch Windows Firewall off for a few minutes, but it'd be nice to know if it's just me or a more general thing.

Update Friday Working fine today - no idea what the problem was.