try wait for 20min if still the same just pull out battery, hold volume up+home button+power key go into recovey and factory reset an wipe cache then restart again see can start or not. the worst case, flash rom with odin again.
ya, we should thanks those developers make things so easy.
i would like to know too. i think DHD might named as ace at US or some where else.
no need to revert, just flash like normal custom rom. www.miui.us
which rom are you on now? to root simply flash a custom kernel will root your phone. as simple as that.
just go into recovery>voodoo control> disable lagfix and system lagfix off>then reboot. after that you will go back RFS. then you can flash any kernel you like.
or
ypu can open voodoo apps >lagfix preferences>untick ext4 convertion and reboot.
i havent flash cm7 or miui before only using cwm for other easy flashed rom.