I purchased a compaq presario PC with Vista Home edition installed on it last
week.
I had to install a usb wireless internet connector. It connected to the net
for the first week but now refuses to do so. it has the icon in the bottom
right corner with the two computers with a cross, but when you click it and
hover above the internet connection it says it is connected, but when you
click on it it tells me that it isnt connected. i try to connect but then it
tells me it cant because of an 'unknown error'. The adaptor is working and it
tells me there is a wireless connection available but it won't let me connect.

does anyone know what it is and if so, how to help me?

Thank you!