Passport 500Gb failed on Mac after doing recommended upgrade

It was working fine and suddenly, after WD’s suggested upgrade, my MacBook Pro Laptop with Snow Leopard will no longer recognize the drive. The drive is not password protected and I use Time Machine on the Mac. Has anyone else had this problem? My complete back-up is on the Passport so I am not big on reformatting it. I bought it to protect myself and now it seems like it is more of the problem. What gives?

I am having the exact same problem! I just upgraded to the newest iMac G5 with Snow Leopard and it is not recognizing my WD My Book (1TB) . I tried both the FireWire cable and the USB. I do not want to reformat either as I transferred data there from my old Mac. I do not want to overwrite, just add new back-up data. Please WD, help. Or any other enlightented Mac Snow Leopard user. Thanks.