Final Cut Pro shuts down/crashes at launch

Question

I never had problems launching Final Cut before. I haven't touched it for about a month, I tried to launch it today. It runs through the splash page where its loading the program -- asks me where my External A/V device is if it's not on -- then I either turn it on and click 'check again' or just click 'continue' either way it finishes loading and the splash screen disappears... then nothing. Final Cut just doesn't launch. I have no idea what's wrong, I would really appreciate help on this, I can't do anything right now
iMac
2.66GHz Quad-Core Intel Core i5
4GB 1066MHz DDR3 SDRAM - 2x2GB
1TB Serial ATA Drive
ATI Radeon HD 4850 512MB
L2 Cache (per core): 256 KB
L3 Cache: 8 MB
Processor Interconnect Speed: 4.8 GT/s

Answer 1

First, it's always a mistake to do any updates to your system regardless of whether they have anything to do with fcp UNLESS you have backed up your system startup drive using a cloning utility. This will allow you to quickly restore your system to it's working state if something goes south.
for deleting preferences:
http://www.digitalrebellion.com/pref_man.htm
This is almost always the first troubleshooting step.
Good luck. Post back and let us know how things work out.