Why does my phone get stuck in a boot loop when it is turned off with an SD card in?

[AC Question]

I've recently had problems with my LG Vigor when I got an SD card for it. I turned it off at one point with the SD card in, and I turned it back on, it would suddenly show the "SD card suddenly removed" warning, then turn itself off. After that, it would get stuck in an infinite loop of booting up and turning off before it even boots up all the way. How do I fix this?