Try to remove the driver manually and install it again. If you have Windows 7, the drivers will be automatically installed. In other case, download them from the official website. Note that this product is not being maintained anymore and it has been discontinued by Netgear.
Another reason for disconnection issues could be related to your system. There is something conflicting with the driver and its software. Close all the background applications and then use the Internet, open one application at the time until you realize what is the software that is causing the disconnection.