I have an IMAC G5 running OS X 10.3.9. I am unable to shut my system down without using the power button at the back. This computer has been a bit of a lemon having gone through 4 logic boards already and I can't get this program/application off of my computer. The program is called .ComcastBoot and when I try to shut down the computer, it pops up in the top applications bar and will continue to time out. I can't force quit it or anything. Has anyone seen this before?