Help! Cannot install programs! URGENT!

Hey everyone, I am working at a Summer camp and am in charge of editing all videos for the summer. I was excited, so I decided to upgrade to Final Cut Express instead of using iMovie all summer. I need to start editing TOMORROW! I just got the program today, but for some reason I cannot install it on my mac! I have run system updater, and my system requirements are enough for the program. However, when I double clicked the "install" icon, a box appeared that said "There is no default application to install..." or something like that. So, I tried updating my software, and I rebooted, and I tried again. Now, NOTHING HAPPENS! I double click the icon, and the dock expands for a split second like it's trying to run something, but NOTHING HAPPENS! Help, guys, I'm really in a bind and I need to get this up and running by tomorrow evening at the LATEST. Thanks!

Everything has been figured out...

Okay, so I messed with it for a long time before finally calling apple. The guy runs me through safe mode, the computer is okay. We create a separate user ID, and try to install it on there. No dice. However, it turns out that some of my utilities had been removed (i.e. INSTALL, DISK UTILITIES kind of important, eh?) so I couldn't do jack. Luckily my friend on staff here has a MBP and I just copied his utilities onto my jump drive and put those on my MBP. Problem solved, I can now install programs. I now have Final Cut Express working great. Thanks for the suggestions, though!