freebsd 7.0+MCP55 SATA Controler

Good day, All.
I've a little question.
I have a MCP55 SATA Controler with SATA HDD attached to it and it worked fine 
on 6.2 until i've decided to install a new system - FreeBSD 7.0
The system usually doesn't even start from this drive, saying:
init: cannot run /bin/sh for /etc/rc: invalid exec format
But sometimes it does and seems to be working, but soon all the services dump 
cores and the system panics. Getting back to FreeBSD 6.2 solves the problem. 
I thought it was memory, memtested it, no errors. And after that I've tried 
to boot 7.0 from this very drive but not through the controller, and it 
worked.

Is the driver for this controller broken or am I wrong about the reason?
Thanks.

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Best regards
Bachilo Dmitry.