A problem that's appeared recently, and which has not been cured by an XP re-install, is where the PCI 802.11g (generic card, non-branded,Marvell Systems chip) card in my desktop will connect well to my WLAN, but after an hour or two, disconnects and won't reconnect unless I view WLANs and force a connect.
Why won't it reconnect automatically.
[XP-SP2, WPA-PSK (TKIP), Linksys WRT54G v2.0 latest f/w]