Hard drive!!!!!!!!!!!!!!!!!!!!!!!! I start my computer and it says NTRDR is missing and cannot go any farther.

Start by trying to do a repair of your filesystem using your original Operating System disk. (What OS are you running)

You should be able to boot from the CD, if not check your BIOS settings and make sure the cd is set to be a boot device. Then go through the installation instructions and select repair, that will reinstall the system files without losing your data.

If the repair works, one of the first things i would do is update your virus software and run a full scan as well as perform a chkdsk /R
to make sure there are no bad blocks on the drive. Something cause that system file to get corrupted.

Let me know if you need more help with this.