No Ping No Remote desktop

Hi, have a weird problem.. have a htpc downstairs with windows 7 32bit Pro and a linksys wmp300n pci card. Anyway my problem is this. I can not ping or remote desktop into that computer unless i reboot the machine. Once rebooted i am able to ping and remote desktop. But once i disconnect the remote desktop after about 10 min or so the computer becomes no longer ping able and remote desktop won't work of course. Now i though the computer was going to sleep so i set the computer for high performance and also set the wireless card to high performnce. but still the problem continues. I also went into wireless properties but the weird thing is there is NO power management tab. If i walk downstairs to access the computer it is on and the wireless is connected and i do have internet. the computer is not sleeping in any fashion it is always on but i won't be able to ping or remote into the computer until i reboot it.

Any help would be great cause i rely on remote desktop to manage that machine

Thanks
Boardgame

Guess no one has any idea about this problem.