My TP started doing that after a while. It'd work for a day or two, then start throwing weird errors about being unable to read files. Then eventually it wouldn't even boot past the POST. I'd boot to the tricolor screen, reflash it, and it'd be fine for a few days. Came to the conclusion that there was some corruption in the internal memory. Flashed my phone back to stock, relocked it, and had my provider replace it under warranty. If you're worried that they won't find anything wrong with it and want to charge you, just mention that the keyboard also quits working sometimes, as that is a common issue.
