I'm baffled. I have an iMac I'm working on for someone, and it keeps booting to an OpenFirmware prompt with the error "bootr - uknown word". Upon investigation of OpenFirmware settings, I discover that the boot-command setting is set to "0 bootr" instead of the proper mac-boot. After setting the boot-command variable to the proper setting and typing mac-boot (or reset-all) the system to boots properly. However, powering off and turning it back on again, and the NVRAM is back to having boot-command set to "0 bootr"!! It's like I can't change it. I've tried with the setenv command in OpenFirmware and with the nvram command in the terminal and even though after setting it I read it and it's set properly, after a power off it's back to the old "0 bootr" value.
It also has another (possibly related??) problem; Quicktime videos have corrupted color; videos play back in black and white, with bands of red, yellow, green, or blue appearing and dissapearing. All videos do this, it's not an issue of corrupted files, it's a problem of corrupted Quicktime, OS, or hardware.
It's a rev A 233MHz tray-loading iMac, with ATI Rage IIC video chip, upgrade to 6MB of RAM. Running MacOS 10.3.5. It's a fresh install of the OS, though the problems did not appear right away. The system was running OS 9, I upgraded the RAM, VRAM and hard drive (to 6GB) and installed OS X. It was running fine for a day or two and then both problems appeared almost simultaneously (first the boot to firmware problem, and then maybe 6 or 7 boots later I noticed the corrupted video problem).
Anybody have any ideas?