Hi I can't open Lightroom 3 it says it has a problem ( but doesn't say what it is ) then it just shuts down
thankyou in anticipation
For starters, you can try either of these two documents:
Troubleshoot system errors or freezes | Adobe software on Mac OS
Troubleshoot system errors or freezes | Adobe software on Windows
These troubleshooters are pretty comprehensive and will point you in the right direction once you're able to target the issue.
Could you give a little more description about the error your having?
Is it possibly something like this: