Samsung Galaxy S II :: Can't Get Past Splash Page

For reasons unknown, after shutting off my phone (I suppose it was a forced shutoff, since the webpage I was viewing had frozen), my Galaxy SII now refuses to go past the splash page/start-up screen, that says "SAMSUNG GALAXY SII". The text will display for about 5 seconds, then the screen will go black for about five seconds, then it will redisplay the text for five seconds, in a never-ending loop.

The phone will charge, and if I turn it off then plug it in I get the standard picture of a charging battery. If I plug the phone in my laptop, the laptop does not recognize that it is plugged in, though the phone does charge.

I've tried getting access to the recovery menu, but I can't seem to get to it - once I push the power button, it enters the splash page loop. The only thing that will end the loop is removing the battery.

I have no idea what I've done to force it into this loop, but it's extremely inconvenient.