I have a desktop w/Intel MoBo Celeron D-3.33ghz. and XP Pro- SP3.

When the computer starts the Boot Screen comes up and then it switches to a screen that lists 2 Window operating systems and ask which one to boot.

The default, or highlighted choice points to a a deleted version. If I am to slow and the countdown to launch starts, I cannot stop it and after trying to start, the screen shows a Files Not Found message. I then have to do a Cold Boot and pay attention so I can select the proper version.

How can I fix this?

You need to change the boot.ini file in C:\.  It may be hidden where you cannot see it.  You should be able to find instructions online on what needs to be changed in it.