Maintain Your Mac
Use Apple's Disk Utility (found in Utilities folder) to Verify/Repair Permissions. Just open it, select the HD or partition to be checked, and click on 'Repair Disk Permissions' - takes less than a minute for a 40GB HD.
To actually repair or fix your HD, you need to bootup from your system CD and use the Disk Utility found on the StartUp screen.
An inexpensive shareware called Macaroni can also be used. This tiny app runs automatically in the background in your System Prefs folder and is very effective at keeping things running smoothly on your Mac..
And, of course, just restarting your Mac once in awhile does wonders for clearing up invisible quirks.
Hammondsport Mac Users Group - Hammondsport, NY 14840 - www.hportmug.com