CPU Running at 100%

First things first. My PC specs is as follows:

Intel Celeron 2.4Ghz D Processor
Gigabyte Motherboard
512Mb Memory
Geforce 128Mb Screen Card

My Question: Every time I try to install Need For Speed: Underground 2 or The Sims 2 University the installation stops just before it ask for the second cd. The Autorun.exe file uses 100% of my CPU time. I’ve install The Sims 2 without any problems and also other programs.

Why is the CPU running at 100%