I have a WPA2 secured network with a visible SSID at home that works perfectly fine with a Dell laptop,a HP netbook and sundry mobile phones. When I try connecting my sister's Lenovo G470, it refuses to detect the wifi network no matter what, but shows up the neighbors' networks. The Lenovo also works correctly at her office. Both laptops run Windows 7. Already tried/checked the following:

• Manually configure wifi network settings (copied over from the Dell)
• Ensure there is no MAC address filtering on the router.
• Ensure router DHCP server is not running out of addresses to assign (I have set it to allocate upto 10).
• Reboot laptop, router etc.

Is this a known problem, and is there anything else one could try?

Update - The problematic Lenovo uses Windows 7 Home Basic while the Dell that works uses Home Premium and the HP netbook uses Starter edition - if that makes any difference.

Further update - It is able to connect if I reboot into safe mode with networking. However in 'normal' mode it shows up the network sporadically, and then says there was an error connecting to it. All the network parameters, password, encryption, etc etc are EXACTLY the same as they are on the Dell.