It could be a software issue, or the button may have lost its connection to the main board somehow. Try pulling your battery (hard reset) to see if that helps, and if not you could wipe the bb and reload the software to see if that does it. You could also take it to a Nextel repair center and have them swap it out (I believe this can be done overnight, so there's not much downtime).
Thanks Martin_j001 - I tried the hard reset already, twice - no luck. I went to the NXTL repair center and they are ordering a new one for me and I will have it by thursday. Only thing was, when I asked if it will be a new one he said it might be a refurbished one. Just amazing how this button just all of the sudden dies. Thanks again. Will let you know if software reload works later tonight.
try a hard reset --- [ take the battery out.. hold power button for 30 seconds, put battery back in, wait for it to boot and run s/w test ] if that doesnt work, reinstall the hhs. then if that doesnt work, service and repair center ;)