Dial up locking up system

I connect to the net via my Sprint phone using the dial up
configuration in windows xp home edition and sometimes (50%
of the time) I cannot disconnect and my computer locks up.
I cannot start any other programs or open any other
windows. I've found that sometimes I can try to reconnect
and that will force the computer to start working correctly
but not always. When this lock-up occurs the two monitor
icons on the tray stay there and I cannot force a
disconnect even when unplugging the phone.
WHAT THE HECK IS GOING ON HERE??? HELP ME OUT MAN!