ICS.MBX.20120422
After I selected 1080p I started AnTuTu Benchmark.
The result was smaller then 720p.
I think it's that because build.prop has this: 'ro.platform.has.1080scale=2'
And your firmware has same string too.
I installed your 201200603_Android_ICS-ATV-108-c03ref
At first it loaded, the master started, I choosed some setup, but after I started work it stopped (no any reaction).
And after rebooting the situation was as schaum wrote - 'It seems to hang on the VPlay animation.'
About ro.platform.has.1080scale=2, I never played with it. It came with Amlogic sources. It's related to screen resolution and screen density. (see set_display_position.sh and reset_display_position.sh under /system/bin)
About box not booting, seems overclocking to 900 mhz was not such a good idea... will update today with original kernel image...