It only happened after the Combo update took the eMac from 10.5 to 10.5.8. The verbose boot showed something with the AirPort Card. Took it out, booted fine. Decided to downgrade to Tiger after that, but when I started this tread I decided to try it again, and so far no problems. eMac runs like a beast, but shadows in the speed of the iMac G4 sitting next to it (faster HDD, processor, and AirPort).