Installer won't launch

I'm helping a newer Mac user set up their MacBook. For now I'm attempting to install their older Illustrator CS and Photoshop CS (until they can upgrade to CS3). When I try to launch the installer icon the application launches for a brief second and then quits. The same thing happens with the trial version of Office. Even though the trial period has not expired; when I try to launch either Word, PP or Excel the application it quits within a second. I have tried verifying permissions and the disk but this hasn't helped. The problem appears to have begun when they downloaded and installed LimeWire.
Any suggestions as to what is the problem?