Hi all,
Weird wireless connection issue, not quite sure were to post this or what info I need to supply.

I've dual booted my old desktop machine with WindowsXP/Lubuntu 12.04. The wireless internet connection works fine in WindowsXP but is generally slower than wireless internet under Lubuntu 12.04 so I'd like to use use Lubuntu.

However, confusingly

Everytime I boot up Lubuntu after powering down the wireless modem/router when Lubuntu was last connected to the router, the system cannot get to the internet even though it's says it's connected to the wireless network. Even weirder, I can't get the internet back under lubuntu until I boot up windows .... confused... ?

As an example

Boot windows, wireless internet good , rebooted into Lubuntu without turning off router, internet good , shut down router/modem, computer,. Come back, turn router/modem on an boot Lubuntu, wireless network says it's connected but can't get anywhere /ping anything.

Essentially it remains like this until I boot windows again, after which the internet will work under Lubuntu, but only as long as the router is powered on. After which the only way I get the internet back is if I boot windows first ....Argh ... So you see it's a bit irritating to have boot Windows then Lubuntu to use the internet!!.

I've tried any number of combinations of powering off, rebooting, disconnecting wireless first then powering down etc .....

Being new at this:
* I don't know what info people need in order to help me.
* How to get that info.

usb wireless adaptor: Edimax EW7711UAn
Modem router: Bt Voyager 2091
OS: WindowsXP/Lubuntu 12.04 dual boot

Any help
Gratefully received