Vista - Unable to access vista share from wireless network

Hi,

I have a HP desktop with windows vista basic. I have setup it up to be
on my home wireless network with PSK encryption. I can see my vista
shares or public folders from my XP laptop on network. The problem
happens when I lock the screen the vista I believe disconnects itself
from the wireless network ergo other PCs are unable to see my vista
shares. I did play around with power settings in vista by setting it
up to max performance so it wouldn't go in sleep mode.
Also changed wireless adaptor settings to keep it alive all the time.
Even if it goes to sleep it should come back whenever anyone tries to
access it's shares.
Has any one encountered similar issue and what was the workaround for
it ?

please advise.

Thanks