dapu,
Without a log, this is going to be guess work.
Go to Drivers & Downloads enter your service tag number, then select your operating system. Under Network, download and install the latest drivers.
Try these tweaks....
Start, control panel, device manager. Click on Network and then right click on your wireless adapter, left click properties, power management. Uncheck the box, allow computer to turn off this device to save power.
Click on advanced. Loof for antenna diversity. Some adapters have this and some don't. If your adapter has antenna diversity, change it from Auto to Aux
Go to the power options, and changed the Wireless Adapter Setting, from Maximum Power Setting to Maximum Performance.
Rick