Read this, it's from a blackberry forum:
"For no known reason the media card all of a sudden disappeared. After turning off and turning on the phone it gave the message that the media card had an error and that I needed to run it on a computer to fix errors. I ran scan disk with no errors and...
...building? I work in a hotel and the phone does not get a signal on the upper floors (3rd and 4th). Is there a way to put antennas in other parts of the building to increase the signal. We currently have a Vtech DECT 6.0Ghz phone. Thanks!