MAC Address Changed... WHAT!!!

I got one for you.. why did the mac address change on my Dell Latitude 600 internal wireless card? No fooling the address had been xx:xx:xx:xx:1A for three years. Then lastnight while synching my new Treo 700W phone to the laptop and later installing a SDIO wireless card into the Treo, my Latitude changed the last octet to 1B. Has anyone ever heard of such a thing. I verified it because I use MAC filtering on my networks and the computer could no longer access my networks. I went in to verify the addy and low and behold the one on the latitude was different from what I had in the access list, not for one but for both networks I run.... Strange I thought that MAC's are hard coded into cards like this.

 

Let me know if anyone has run into this.