My mid 2007 MacBook was working fine until about six months ago. Lately, though, it's been going through periods of sluggishness. Sometimes it works fine, but other times it runs very slowly or freezes up. When it freezes, it sometimes beachballs, but sometimes just freezes without any beachball for up to a minute. All applications run fine sometimes, but very slowly other times. Sometimes I switch from one "Space" to another and it freezes half way through changing, with the four quadrants displayed. Sometimes when typing an email or on a forum, the text stops showing up and then appears 30 seconds later. I tried to reinstall Snow Leopard by inserting the DVD and holding "C," but my drive just spun around and spat the disc out again. I tried using the Tiger disc that came with the machine, but it did the same thing. I thought it might be the drive, so I bought an external. The discs spun around, an icon showed up on the desktop, and a folder popped up. But then the icon disappeared, reappeared, and another folder popped up. This repeated until I stopped it. The same thing happened with the Tiger disc. Anyone have any ideas? Is it time to give up on this machine and get a new one, or are there any other tricks I could try? Here are the specs: Mid 2007 White MacBook (NOT PRO) OSX 10.6.8 (Snow Leopard) 4GB of Crucial RAM (Apple says 3 max, but Crucial stands by 4) 500GB Western Digital Scorpio Black HD Thanks!