login to account, only purple screen opens

jkrcvt,

If your profile is correct, and you in fact running 10.6.5, you should update Snow Leopard to 10.6.8 via the combo update. Here is the link:

Mac OS X 10.6.8 Update Combo v1.1

If you are in fact up to date with 10.6.8 try a NVRAM reset:

1. Shut down your Mac.
2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R.
3. Turn on your Mac.
4. Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
5. Hold these keys until the computer restarts and you hear the startup sound for a second time.
6. Release the keys.

You can also try a SMC reset:

Intel-based Macs: Resetting the System Management Controller (SMC) - Apple Support

Follow the directions for your machine, for a battery you can remove yourself, or a battery you should not remove yourself.

Are you able to do anything? It is unclear to me if you have booted completely or it froze during startup.