It's my guess the problem is similar to my system. I am unable to run LW 4.18 or LW 5 on my main OSX system. Despite doing a few OSX archive re-installs last year, that did not solve the problem. I used my old bootcamp partition for windows & reformatted it. Installed OSX onto it. Installed LW 4.18 & it worked fine. Installed LW 5 when it came out, worked fine ever since. So something was wrong with my original OSX installation. So last year I should probably have done an "Erase and Install" instead on my main OSX. I just didn't wish to have to go thru the pain of backups, reinstalling all softwares again.

Perhaps that is not your problem. Set up another account, a test account: Setting up a Test Account in OSX (click on link). Try opening LW from there. Also try SAFE Boot & Repair Permissions.

You could try reinstalling OSX using the combo updates; Apple - Downloads - Mac OS X - Mac OS X Updates or alternatively a java update: Apple - Downloads - Mac OS X - Application Updates. This used to be a fix for OSX 10.4 & earlier, but not sure if it works for Leopard. There seems to be no OSX or Java receipt files either. I just tried the last Java update, seemed to install ok. BTW should normally repair permissions after installing any software, especially system software such as OSX updates or Java & some other 3rd party program updates.

thanks dont know how did the test account thing and it started to work on my main account thanks for all your help problem solved somehow :S lol