Imac display problem

Apple newbie here.

I was given a old imac. It's white, has 2.16 Ghz processor, 3GB RAM and the latest version of OSX.

I am a having two problems with it.

1. Seemingly at random, lines of varying length, one or a couple of pixels tall, appear on the display. Within each line the pixel by color appears to be random.

2. Sometimes I will click on a website or launch something and I get the multicolored wheel. The machine freezes and the wheel keeps going round and round and round. This seems to happen most frequently when making a video full screen. I wind up turning the machine off and restarting it.

Any ideas as to what's wrong? Video card? Video card memory?

I'd post a picture of the lines on the display but I don't know how to snap a screen shot yet.

 

I see two possible things here you should try doing.. ( Reset PRAM & And Pull user Preferences to the Trash if issue occurs in a Test user. )


1. Shut down the computer.

2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.

3. Turn on the computer.

4. Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.

5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.

6. Release the keys.

Some information stored in PRAM includes:
Display and video settings such as refresh rate, screen resolution, number of colors
Startup volume choice
Speaker volume
Recent kernel panic information, if any


2. When the computer boots up and when you make use of the applications and the spinning pin wheel occurs it can mean the following.. A .Plist file has been corrupted in the home users folder or within the Root level some common corruption has occurred and that the Hard Drive may need to be scanned in Disk utility and repaired.

You can try the following.. ( After the PRAM has been reset )

Also, before doing the following make sure you test the issue in a new user account. IF the ISSUE does NOT OCCUR in the new user then please attempt the following... IF the ISSUE does OCCUR in the new user, then repair the hard Disk using Disk utility when booting to the Install DVD.
Do this if the issue does not occur in the new user account.

1. Boot the computer in to safe boot ~ Power the computer off.. Start the computer while holding shift.. Let go of the Shift once you see the Apple and the spinning gear..

2. Log in ( If you have to ) like you normally would, you should see Safe Boot or Safe mode.

3. Navigate to your home folder.. Open the finder ( Blue face along your dock ) select the home folder ( Picture of a house ). You should see Documents, Pictures, library and so forth. Select library and then remove preferences to the desktop or the trash can.

4. Restart the computer normally ( Keep in mind if you have anything stored in mail it will be lost and that you will have to set up mail all over again. )

5. Test to see if the issue occurs again.

Hopefully this helps. Sorry for any spelling mistakes.

 

Thanks AirSinner.

Everything checks out clean except it wouldn't let me trash the library folder. It tells me that it's needed by OSX.

There is something else very strange. When I check file system permissions, I get a whole list of file permission errors. I fix them and then the next day when I run the file system check again the file permission errors return.

I found some posts on the web which indicate it might be heat related or a bad board. I installed a smcfancontrol but I think its hardware related as the lines appear upon startup when the machine temp is 70 degrees Fahrenheit.