when typing, letters jump out of order or turn blue and erase

Hello,

Do you have another Mouse & Keybord to try?

"Try Disk Utility

1. Insert the Mac OS X 10.5 Install disc, then restart the computer while holding the C key.

2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu at top of the screen. (In Mac OS X 10.4 or later, you must select your language first.)

*Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.*

3. Click the First Aid tab.

4. Select your Mac OS X volume.

5. Click Repair Disk, (not Repair Permissions). Disk Utility checks and repairs the disk."

http://docs.info.apple.com/article.html?artnum=106214

Then try a Safe Boot, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot when it completes.

(Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive & clear caches.)

If perchance you can't find your install Disc, at least try it from the Safe Boot part onward.

I use AppleJack at least once a month with the following command:

applejack AUTO shutdown

Are you using 10.5.7 or is your signature out of date?