So far since updating, Safari, Finder and Youtube have white bars and flashes when I use them for no reason. My printer will not work, and my internet has slowed down (no idea what is going on their). Is their anyway to go back to 10.5.1?
Why not just an archive and install. Your system folder may have just gotten corrupted. I have had nothing but the best experience with my iMac since updating to 10.5.2.
In your Applications folder, open the Utilities folder, then open the Disk Utility icon. Once Disk Utility is open, make sure your main HD is selected in the left-hand window (if you have more than one drive), then click on "repair permissions" in the lower right-hand corner of the dialogue box. It will take a while to run. After it finishes, close and reboot.
If you're up for it, try reapplying the update. Personally, I'm not optimistic; I've had nothing but problems trying to apply the 10.5.2 update on three of my six machines, and I'm meticulous about keeping my disk permissions repaired. BTW, "repair your disk permissions" is pretty much the Mac equivalent of the panacea "take two aspirin and call me in the morning": it's not the solution to every Mac problem that some would have you believe.
To get back to 10.5.1, do an archive and install from your original Leopard disk. If it's a 10.5 disk (rather than the 10.5.1 version), you then need to apply the standalone 10.5.1 update, available from the Apple site. By that time you'll probably have to update some of your preferences, etc.: failed 10.5.2 updates have a nasty habit of leaving a mess behind.