This happens to me too. I have HTC Inspire. My husband has the same phone, but it never happens to him. I guess, this bug affects only certain phones. I called tech support, they told me to do factory reset. I did the reset but it didn't fix anything at all, the bug is still there.
Some people say they told to make a video of it, but it would be very hard to do because it doesn't happen every time, only some times. I've been trying to show my husband what happens, but he haven't seen it yet because you just never know when it's going to happen again, and when it happened it's too late.