Hi all I'm a new member here. The problem that I have with my MDD is the OS. I installed OS X 10.5 just fine on an 80GB hard drive that I purchased the machine with. The problem is that it wont let me install any applications its really weird. I cant mount DMGs unless i manually click on the window to skip validatingl even after this some applications dont install correctly or at all. I thought maybe it was a firmware issue, but its up to date. Then i updated the software to 10.5.8 and still the probelm persists. I thought maybe it was some of the applications I was installing but it turns out its most of them! what should I do or what could the problem be? I was thinking maybe to install Tiger on the Hard drive and then just upgrade to Leopard over the Tiger installation. I'm not sure what to do and its driving me nuts! Please let me know your thoughts or suggestions on this problem, and thanks in advance!!