HI,
Try booting in
Safe Mode
Safe Mode deletes font caches which may help. It can take a few minutes to boot into Safe Mode compared to a normal boot. Once you are in Safe Mode go to the Apple Menu and click Restart.
What is Safe Mode
Also, your forum profile indicates you are running 10.4.3. If this is the case updating your system software may help also. Go to the Apple Menu/Software Updates.
And try repairing disk permissions.
Quit any open applications/programs. Launch Disk Utility. (Applications/Utilities) Select MacintoshHD in the panel on the left, select the FirstAid tab. Click: Repair Disk Permissions. When it's finished from the Menu Bar, Quit Disk Utility and restart your Mac. If you see a long list of "messages" in the permissions window, it's ok. That can be ignored. As long as you see, "Permissions Repair Complete" when it's finished... you're done. Quit Disk Utility and restart your Mac.
Carolyn 🙂