BB Curve :: Unresponsive Keys And Blsnk Screen?

when i grabbed my phone , the screen was blank, and the keyboard unresponsive, the phone was still receiving text messages and phone calls, but did not allow me to answer. I tried taking the battery out of the phone, and when i did that, a "no battery" symbol appeared, so i then knew that the screen was not damaged. When I put the battery back in, the screen went blank again. The battery must be charged, otherwise it would not allow phone calls to come through.