SMB over lan works, but not over wifi

Ive set up a number of computers in our network to share files with my mbp through smb, and it always worked fine and still does, as long as I have the lan cable connected. When I switch to wifi, it cant connect to the server. Internet and everything works fine.

I have 2 APs, one is the router and the other is connected to the same switch as where I plug in my mpb and one of the shared PCs. If I reboot the mbp to XP and connect to the network with wifi, and the sharing does work fine. Can anyone help me troubleshoot this?

This problem exists both on MBP and PPC machines. I think the recent issue is related to an WS2003 update a ran in July. I moved 1 share to my XSERVE to solve a client share issue, but I can't keep moving shares because my mac clients want to access them. MS has blown something with a recent security update. They need to fix it. Apple blew it in January of this year but quickly fixed it and now MS has blown it. I wonder how long it will take them to fix it.