Intel Mac :: Finder Keeps Relaunching Over And Over Again?

I recently used a theming application on my iMac called theme park and it screwed up my Mac, when I log in my finder boots up then crashes then relaunches and continues this over and over again, I tried restarting, and logging into a different account and it just won't work, when I try to open up an application it crashes as finder relaunches and a pop up appears saying the application quit unexpectedl, when I right clicked on the finder icon on my dock it says all the options like open folder, then a second later it changes to application not responding. Btw I can't access the "about my mac" pane but I do know that it is an intel based iMac with the glossy white appearance not the aluminum model and I think it's the iMac6,1 I don't have a time machine backup or restore disk 

Info:
iMac, Mac OS X (10.5.8), iMac6,1