WMP110 Frequent Internet Connection Loss

Since installing the Linksys WMP110 wireless adapter on my Windows XP SP2 desktop, I've been losing connection to the internet every 5 minutes. Oddly, the signal to the router is always full bars.

Though Linksys sent a replacement, I'm still having the same problem. None of the troubleshooting procedures they've suggested have worked; hence my post here. Below are the failed procedures to my recollection.

Router Linksys WRT54G:
+ Update firmware
+ Try various modes
+ Try various channels
+ Change the beacon interval, rts, & fragmentation

+ Update driver for the adapter
+ Set wireless properties to 'Access point network only'
+ Install adapter to another cpu
+ Disable firewall, antivirus, spyware programs

One suggestion I couldn't try was ... connecting to an unsecured network as all networks detected in my area were secured. My laptop, which has a diff wireless adapter but is placed in the same location as the desktop with the problematic adapter has never lost connection to the internet.

Why am I losing internet connection and how can I prevent it?