I had that happen once, where I set the boot.ini to boot into safe mode and it went into the same loop that you are referring to. That was the day I died a little.
I was finally able to get in and uncheck that box which ended the loop, but I have no idea how I did it, and was probably not myself when this was going on. I was in a mad rage...so my memory was fried. I want to say that I finally got the chance to boot into safemode with one of the Function buttons...but I remember trying them ALL numerous times before something let me in.
__________________
|