Try using the X2 4979 bios,
I'm having the same troubles as you using any of the others.
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It won't be long untill XBTC will contain all these functions itself.
Eventually (if development & interest continues at the current rate) we are looking at having it as one compleate application...
You create your .x file, choose what colour you want the text & the flubber, and hit go, and out pops a fully modded bios.
But this will take time... maybe 2-3 months, who knows it could be sooner. We might even get round to making it run on the XBox.
One thing it wont include though (for now) is support for the 4983 or the M8 bios's.