Linksys WAG200G VPN problem

Hello

I'm with O2 and have a reliable service with a down rate of about 14Mb/s and
an uprate of about 1.2Mb/s.
The O2 router seems to be playing up a bit with many random disconnects for
no apparent reason.
So, I've ditched that and reconnected an old WAG200G. This also connects
with similar speeds. But the issue I have now is that when I establish a VPN
connection, when the connection is idle for about 40s, it disconnects and
then attempts a redial.
If the link is not idle, then there are no issues.

This is using WinXPproSP3. The VPN network connection's properties seem to
be correct and the idle time is set to "never". It all worked ok with the O2
router.

The only cure is to either keep the link busy, or run tunnelrat.

Any suggestions?
Ta.