Mac Book stalls after sitting, takes a long time to run programs then

First, upgrade your OS. You post you are running 10.6.5, however the latest version is 10.6.8.

How much free space is on your computers Hard drive??

Next, try the following basic troubleshooting:

REPAIRING DISK PERMISSIONS -

NOTE: refer to article "About Disk Utility's Repair Disk Permissions feature" found herehttp://support.apple.com/kb/ht1452 - for the actual apple article on these step. ----

- click finder in the bottom dock, and in the window that opens, select applications in the left column - scroll through until you see the 'Utilities' folder and double click to open it. Then double click on 'Disk Utility'

- When prompted to select a disk volume or image, select the 'Macintosh HD' in the left column

- ensure the the "first aid" tab is highlighted blue in the middle of the screen

- click the button at the bottom that says 'Repair Disk Permissions'

- this process will take a few minutes to run. It will indicate it's done, by scrolling to the bottom of the "details area" displaying 'Permissions repair complete'

Dan Frankes has written an excellent article for Macworld on "Permissions" and the need to repair them - see - http://www.macworld.com/article/52220/2006/08/repairpermissions.html.Another good web site is - http://www.thexlab.com/faqs/durepairfns.html.

REPAIRING DISK

NOTE: refer to article "Resolve startup issues and perform disk maintenance with Disk Utility and fsck" found here - http://support.apple.com/kb/TS1417 - for the actual apple article on this step. --

Also see - http://support.apple.com/kb/HT1452.

- with computer on, insert the computers "install disk 1" or "Mac OS X Install Disk" into the optical drive.

- shut down computer

- restart computer holding down the letter 'C' on the keyboard. Keep holding down the 'C' key, while the computer powers on, and continue to hold the key down, until you see a screen appear, asking for you to select a language. This may take a minute or so to appear. When this screen appears, release the 'C' key

- select english, then the continue arrow in the lower right corner

- the next screen will display "Welcome to the Installer". On this screen, we want to look into the top menu bar (beside the apple in the top left corner) and select 'Utilities' , then 'Disk Utility' ---

- When prompted to select a disk volume or image, select the 'Macintosh HD' in the left column

- ensure the the "first aid" tab is highlighted blue in the middle of the screen

- click the button at the bottom that says 'REPAIR DISK' .......NOT "Repair disk permissions"

- this process will take a few minutes to run. It will indicate it's done, by scrolling to the bottom of the "details area" displaying "The Macintosh HD appears OK"

If you get any other message OTHER than "The Macintosh HD appears OK", like "the Macintosh HD was repaired successfully" run the "Disk Repair" again, until it displays "The Macintosh HD appears OK".

Once done, beside the apple, click on the words "Mac OS X Installer", and select quit / restart. On the keyboard, hold down the eject key (top right corner, grey triangle pointing up, with a line underneath) until the disk ejects from the drive. Just let the computer start up normally.

NOTE - if you don't have or can't locate the install disks, you can follow the section 'Use fsck' of the same above article to boot into single user mode, and run the /sbin/fsck -fy command. This essentially runs the same test, that is on the install disk, just without the disk present---