Wirelessly posted (HTC Diamond: Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 8.12; MSIEMobile6.0) Sprint T7380)
Have you tried a soft reset lately?
Push the red button under the battery door.
You may need to do a clear storage/hard reset to fix it.
Otherwise you could have a hardware problem with your power button.
