I had this happen last night, the ATV has been on for a few days, maybe a week or more. All working fine. Last night, went to watch some things on iPlayer, and it would not come out of sleep mode, it was ignoring the IR remote, the white light on front of the ATV was not flashing.
So a quick power cycle. System boots, then I start boxee, it exits with this error code 6.
I power cycle again, this time it trys to loging, but then asks me for the password it usually remebers. I enter the password, this works. But I then find the screen is out of alignment and I have to reinstall TVcomposite.kext for my PAL SCART TV.
It was working again last night, have not looked this morning.
pzboyz ATV 3.02, Boxee Beta 0.9.22.13692
Sony 40z4500, ReadyNAS Duo 2TB.