I have something very similar on my setup. There is a problem with the BT ADSL setup that can cause the line to get into a state where it appears from both ends to be connected but no traffic passes. When it gets into this state the only way to fix it (without phoning up the ISP's support line to get them to reset the session), is to logout, login as the BT test account and log back in normally.

I can't afford for the line to get into this state when I am away (my domains would fallback on their secondaries until I reset it all). I therefore have an expect script on my Linux box that telnets to the router and does the magic logon-logoff trick.

I run this once a day, every day, from my crontab. That way I get just under 15 seconds of downtime everyday, but at least I don't get stuck with my line down and me hundreds or thousands of miles from it. Thankfully, even if I am using the line at the time I rarely notice the 15 seconds of downtime (thank God for TCP).