Atheros AR5001X+ wireless network adapter

Hi,

I'm using a Toshiba Satellite A45-S150 notebook and it has a built in Wi-Fi 802.11g with Atheros AR5001X+ wireless network adapter.
I always used to get Excellent signal strength and the internet speed was good..I was out of the country for a month and after coming back now the signal strenght is always Low...My friends get Excellent signal strength...One of them has same toshiba notebook with the in-built Wi-Fi and the other has a network card...

If i use the network card..signal strength is Excellent...

I've tried updating the Atheros AR5001X+ wireless network adapter also..

Any suggestions are appreciated..

Thanks
Sachin