Power management on adapter card may be?
Go to the properties of your wireless adapter card in device manager and make sure both boxes are un-check in power management tab.
---------- Post added at 23:12 ---------- Previous post was at 22:23 ----------
Might not be above found this on sonys US site:
Wireless connection issues using the LAN-Express (Atheros) wireless network adapter
http://www.kb.sony.com/selfservice/m...&mdl=VGNNR110E
If you want to try the above, here's Sony's UK support page for driver updates for your modem VGN-NR10E/S:
http://support.vaio.sony.co.uk/downl...=VGN-NR&m=2866
If your current software / driver version numbers don't tie up with these, I would suggest you update them.
VAIO Smart Network -2.0 - 2.0.1.11050
and
Wireless LAN Driver (Atheros) -7.4B - 7.4.2.15