I have a 15" 3 year old Powerbook that I'm running Leopard on. About a week or so ago I started having problems with my iChat when it randomly started crashing. Then my Yahoo Messenger and Safari started doing the same. I didn't know what to do, but just stuck to using AIM and Firefox instead. And I would occasionally try the other ones... now one of them even finish loading before the program crashes. I deleted iChat off my computer and went to go reinstall it, and the installer quit. Now I'm obviously convinced that my computer has a virus, but I can't download a virus scanner or any sort of antivirus program to help deal with the program because I can't install any programs on my computer. I'm so beyond pissed and frustrated I'm ready to throw the piece through the window. Is there anything that I can do short of reformatting my entire hard drive?