3Com 11g Router / Card Dropping Connection

I recently purchased a 3Com Office Connect Wireless 11g ADSL Modem/Router
which came bundled with a card.

I've got the card installed in a Laptop with WinXP Pro, and it works fine
most of the time but sometimes the connection just drops for no reason and I
have to do one of two things and then it works fine.

Remove Card from Laptop (usually fixes problem - but not always)
Reset Router

Sometimes when it disconnects it then says it's found my network (in the
taskbar balloon hint) but it won't do anything when I press the connect
button.

I've tried changing channels, WEP on/off, using/not using 3Com's card
manager software but it still happens. It can work for 15 hours or so and
then next time only 10 mins.

Any ideas or pointers as to what could be wrong ? Faulty hardware?

Thanks

Ben