lightroom #4 problems

it seems when i start up lightroom the last week or so it will freez up the computer before it loads up! 2-3 min later it will load,could any one tell me whats going on hear ! and until it loads i can't do any thing on the PC.do you think i should start a new catalog or some thing like that,thanks for some help.

have you checked if other programs are running in back ground ,, antivirus checking files have you got any other programs running at same time .maybe memory full ?
or have you added large amount of pics to catalogue ..maybe worthwhile backing up catalogue and reinstalling LR or optimising catalogue etc
hope you find the problem

Give us details of your computer specs, inc CPU, RAM, all the disks inc external, OS, etc. Any other software? What's happening in task manager/resource monitor when it's frozen? Is it using a lot of CPU or disk? If disk what is it accessing. If CPU what process. When did it start?

Google to learn how to get to task manager / resource monitor. Short answer, control shift esc, then in performance tab there's a button.

Try optimizing your catalog if you haven't already done so. Open the program and then go to File > Optimize Catalog.