Start the computer from an external start-up disk, such as the system software CD that came with your computer. Also note any error messages. Try to replicate the problem if you can. Be as specific as possible when talking to the support person. With my iMac CD, though, the computer boots normally.
Computers tend to crash or hang when their hard disks become too full.
Free up space by deleting unnecessary files and emptying the Trash or Recycle Bin. When working inside the computer, turn the power off but leave the electrical cord plugged into the surge suppressor. Ground yourself by touching the casing of the power supply before touching any of the computer's circuits. Inc. How things get done. Use of this Web site constitutes acceptance of the eHow Terms of Use and Privacy .