E4200 router, wmp600n wireless adapters and mapped drives with wpa2 don't work!

Question

Sigh
I have a file server running windows 2003 and five computers (1 windows 7, 4 windows xp-sp3).
There are two shares on the server.
When the router is setup with wpa2, three of the windows xp machines will have problems with mapped drives. Directly after the drives are mapped, everything works, but 10 or so hours later, users can no longer access these mapped drives and there is no way to reconnect them it seems.
The other two machines (windows 7 and one windows xp machine) have no problems whatsoever.
The only thing that the three computers have in common is that they are also sharing a printer (an hp j4680) attached to one windows xp machine (not the server).
If I set everything to wpa, everything works fine, but of course my wireless network speeds drop to 56mbps.
Thoughts?

Answer 1

Peanut, I appreciate your effort, but I don't think you truly understand what is going on.
FWIW and for those experiencing similar oddities, On a mixed network of Windows Server 2003, Windows XP and Windows 7 machines, several Windows XP machines would on boot up decide that the router was the master browser. This made file shares on the server inaccessible to these machines. All machines were using wmp600n adapters.
All computers had excellent signal strength and could access the internet without fail.
What was not immediately evident to me was I was also having email issues where certain XP machines could not receive or send (sometimes one, sometimes both) pop email. I suspected it was a port blocking issue by the ISP since this problem was intermittent.
What was clear though is that in each of the machines that exhibited the problem that computer was seeing the browser as the browser master. So finally, I swapped out the router with another branded router. This is not the only case of this router behaving this way--in my searches I have run into several other people who have had issues with file sharing so I don't know if it is a model deficiency or firmware issue.
All I know is the all the problems went away with the router switch.  File shares work. Email works.
So, I got a bad router that appeared to function properly--assuming this is not the case with other e4200s. I will know after RMAing this one.