Problem description: Just lately my finder (or maybe trackpad) seems to have a mind of its own - switching between tabs in my browser and generally dingiest own thing regardless of what I try to do. It makes MacBook (late 2009) (with OS 10.10.1) Cayn

That Mac is being affected by CleanMyMac as well as MacKeeper. Other reasons for the behavior you describe are possible, but having been affected by them, it is not reasonable to expect normal operation.

MacKeeper's uninstallation instructions will remove it effectively, but CleanMyMac's uninstaller will not rid your Mac of all its components. EtreCheck does not reveal their presence. Reinstalling OS X will have no effect.

Either of those products are capable of causing corruption that cannot be reversed by merely uninstalling them. If they have been used to alter OS X or your essential software, the most expedient recovery method is to erase it completely and reconfigure it from the ground up, reinstalling only your essential software and other files. "Essential software" is defined to specifically exclude such garbage "cleaning" utilities.

How would you like to proceed?

Is there a reason you are not using Time Machine?

There are several possible causes for this issue. Please take each of the following steps that you haven't already tried until it's resolved. Some may not apply in your case.

1. Follow the instructions in this support article, and also this one, if applicable. A damaged or defective AC adapter could be the cause, even if it's the right kind.

2. Press down all four corners of the trackpad at once and release. If there's any effect, it's likely to be temporary, and in that case the unit must be serviced or replaced.

3. Open the Bluetooth preference pane in System Preferences and delete all pointing devices other than the trackpad, if applicable. Disconnect any USB pointing devices. By a "pointing device," I mean a peripheral that moves the cursor, such as a trackpad, mouse, trackball, or graphics tablet. A plain keyboard is not a pointing device.

4. Start up in safe mode and test, preferably without launching any third-party applications. If you don't have the problem in safe mode, but it comes back when you restart as usual, stop here and post your results. Do the same if you can't start in safe mode. If there was no difference in safe mode, go on to the next step.

5. Reset the System Management Controller.

6. If you're using a Bluetooth trackpad or mouse, investigate potential sources of interference, including USB 3 devices.

7. A swollen battery in a portable computer can impinge on the trackpad from below and cause erratic behavior. If you have trouble clicking the trackpad, this is likely the reason. The battery must be replaced without delay.

8. A defective peripheral device or a damaged cable can cause the built-in trackpad of a MacBook to behave erratically. If you're using any wired peripherals, disconnect them one at a time and test.

9. There's also a report of erratic cursor movements caused by an external display that was connected but not turned on.

10. If none of the above applies, or if you have another reason to think that your computer is being remotely controlled, remove it from the network by turning off Wi-Fi (or your Wi-Fi access point), disconnecting from a Bluetooth network link, and unplugging the Ethernet cable or USB modem, whichever is applicable. If the cursor movements stop at once, you should suspect an intrusion.

11. Make a "Genius" appointment at an Apple Store to have the machine and/or external trackpad tested.

The reason for asking is that it's a personal decision that only you can make, having personally decided the value of your time. Having said that, if it were my Mac I would be satisfied with nothing less than erasing it and reconfiguring it as described below, for the reasons specified.

All those "cleaning" programs are scams designed for one and only one purpose: to take your money. A suitable backup hard disk drive of adequate capacity can be purchased for the cost of either CleanMyMac or MacKeeper. The cost of both of them together will purchase one with abundant capacity. If you value the information on your Mac, a backup is not a luxury; it is a requirement. Time Machine is already included in OS X and facilitates routine, automatic performance of what would otherwise be a mundane task. Using it is explained below.

Lastly, bear in mind what I wrote earlier: other reasons for the behavior you describe are possible.

There is no practicable way to reverse the effects of having used CleanMyMac2 other than to reinstall all affected files from backups or their original sources. Its developer's uninstallation instructions are ineffective despite their recent claims to the contrary. Only MacPaw, its developer, can know the reason for that, but I can think of two possibilities: either they are purposefully leaving components behind for reasons known only to them, or they simply don't know what they're doing. Neither one of those possibilities is particularly comforting for the user.

Reinstalling OS X alone will have no effect on either removing CleanMyMac or reversing the damage it is capable of inflicting upon a system.

Follow the applicable recovery procedure below:

• If you have a backup that you created prior to using CleanMyMac, now is the time to use it. For Time Machine, boot OS X Recovery, and at the Mac OS X Utilities screen, choose Restore from Time Machine Backup. Choose a date preceding the installation of CleanMyMac.
• If you do not have a backup that predates the use of CleanMyMac, create one now. To do that read Mac Basics: Time Machine backs up your Mac.
  • The recovery procedure will require that you erase the Mac using OS X Recovery, and then create a new user whose contents will be empty. You will then be able to use Setup Assistant to migrate your essential documents including photos, music, work products and other essential files.
  • When doing so, select only your previous User account and do not select "Applications", "Computer and Network Settings" or "Other files and folders". De-select those choices.
  • Subsequent to using Setup Assistant, you will need to reinstall the essential software you may require, once again remembering to install software only from their original sources, and omitting all non-essential software.

To erase and install Yosemite read: OS X Yosemite: Erase and reinstall OS X

To migrate your essential documents read: OS X Yosemite: Transfer your info from a computer or storage device and follow the procedure under Transfer info from a Time Machine backup or other storage device.