IMac system stops responding repeatedly

Question

Hi,
My iMac running on Lion Os is having some serrious issues since a while. It starts up without a problem but after a little while most things stop responding to mouse clicks or clicks suddenly provoke closure of windows and sudden scrolling. This happens on a daily base and most of the time rebooting( or updating) does not resolve the issue and the symptoms are getting worse. Sometimes the computer will just stay stuck from the start and only the side bar will react to the mouse clicks. It really reminds me of  a virus from back in the windows days...Thx.

Answer 1

Remove the "MacKeeper" crapware as follows. First, back up all data.
Note: These instructions apply to the version of the product that I downloaded and tested in early 2012. I can't be sure that they apply to other versions, nor do I intend to repeat the test.
IMPORTANT: "MacKeeper" has what the developer calls an “encryption” feature. In my tests, I didn't try to verify what this feature really does. If you used it to “encrypt” any of your files, “decrypt” them before you uninstall, or (preferably) restore the files from backups made before they were “encrypted.” As the developer is not trustworthy, you should assume that the "decrypted" files are corrupt unless proven otherwise.
In the Finder, select Go ▹ Applications from the menu bar, or press the key combination shift-command-A. The "MacKeeper" application is in the folder that opens. Quit it if it's running, then drag it to the Trash. A dialog will pop up asking why you want to uninstall it. You don't have to provide that information. Enter anything you like in the text box, then click the Uninstall button. All the functional components of the software will be deleted. That's the only useful feature of "MacKeeper:" it deletes itself. Reboot.
Do not try to uninstall by dragging the MacKeeper icon in the Dock or the LaunchPad to the Trash.
Here are some general suggestions. If you want your computer to be usable, don't install crapware, such as “themes,” "haxies," “add-ons,” “toolbars,” “enhancers," “optimizers,” "tune-ups," “accelerators,” “extenders,” “cleaners,” “defragmenters,” “firewalls,” "barriers," “guardians,” “defenders,” “protectors,” most “plugins,” commercial "virus scanners,” "disk tools," or "utilities." With very few exceptions, this kind of material is useless, or worse than useless.
The more actively promoted the product, the more likely it is to be garbage. The most extreme example is the “MacKeeper” scam.
The only software you should install is that which directly enables you to do the things you use a computer for — such as creating, communicating, and playing — and does not modify the way other software works. Never install any third-party software unless you know how to uninstall it.