AirPort/Linksys Router Madness

[Oysterville]

I'm running a network with a Linksys router in the back room and a Mac AirPort access point out in the main shop that is connected to the Linksys. When PC laptops connect to the AirPort all is well; however, if a Mac laptop connects to the AirPort it freezes up my Linksys to the point that I have to power cycle it for things to be back to normal.

Any ideas why this is happening ONLY when a Mac connects? It's a head-scratcher for me.

 

[Oysterville]

Update: If I reset the Linksys with Mac folks connected to the Airport, surfing is fine for awhile before it locks up again.

 

[networkman]

Any Mac? Or the Mac that happens to be available? I'm thinking infection/malware of some sort.

 

[Oysterville]

I was hoping it was just one Mac, but it happened with three different Macs in one day.