Mac os lion launch pad issue

I just recently updated to Lion on my 24 inch I-mac with no issues. A couple of days ago when I hit launch pad ( rocket icon looking app) my computer totally locks up where I have to hold the power button to turn if off then reboot it. Don't understand why it's been doing this all of the sudden but was wondering if anyone else is having this issue. If you are experiencing this, let me know if there is anything I can do. I have MAC OS LION on all my other macs with no issues.


Eddward