Search engine preference is google, but when i search it switches to bing

Question

On my macbook pro which is using mountain lion, by safari search engine preferences is set to google, but when i enter a search term it defaults to bing.  Only noticed this problem after downloading adobe flash player for what it's worth.

Answer 1

You installed the "Genieo/InstallMac" rootkit. The product is a fraud, and the developer knowingly distributes an uninstaller that doesn't work. I suggest the procedure below to disable Genieo. This procedure may leave a few small files behind, but it will permanently deactivate the rootkit (as long as you never reinstall it.)
Malware is constantly changing to get around the defenses against it. The instructions in this comment are valid as of now, as far as I know. They won't necessarily be valid in the future. Anyone finding this comment a few days or more after it was posted should look for more recent discussions or start a new one.
Back up all data. You must know how to restore from a backup even if the system becomes unbootable. If you don't know how to do that, or if you don't have any backups, stop here and ask for guidance.
Step 1
In the Applications folder, there may (or may not) be an application named "Genieo". Genieo may be partially installed even if this item is absent. If it's present, select it and open the Finder Info window. If it shows that the Version is less than 2.0, download and install the current version from the genieo.com website. This may seem paradoxical, since the goal is to remove it, but you'll be saving yourself some trouble as well as the risk of putting the system in an unusable state.
There should be another application in the same folder named "Uninstall Genieo". After updating Genieo, if necessary, launch "Uninstall Genieo" and follow the prompts to remove the "newspaper-style home page." Restart the computer.
This step does not completely inactivate Genieo.
Step 2
Don't take this step unless you completed Step 1, including the restart, without any error messages. If you didn't find the Genieo application, or if you couldn't complete Step 1 for any reason, stop here and ask for instructions.
Triple-click anywhere in the line below on this page to select it:
/Library/Frameworks/GenieoExtra.framework
Right-click or control-click the line and select
          Services ▹ Reveal in Finder (or just Reveal)
from the contextual menu.
If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination command-C. In the Finder, select
          Go ▹ Go to Folder...
from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.
A folder should open with an item named "GenieoExtra.framework" selected. Move that item to the Trash. You'll be prompted for your administrator password.
Move each of these items to the Trash in the same way:
/Library/LaunchAgents/com.genieo.completer.update.plist
/Library/LaunchAgents/com.genieo.engine.plist
/Library/LaunchAgents/com.genieoinnovation.macextension.plist
/Library/LaunchDaemons/com.genieoinnovation.macextension.client.plist
/Library/PrivilegedHelperTools/com.genieoinnovation.macextension.client
/usr/lib/libgenkit.dylib
/usr/lib/libgenkitsa.dylib
/usr/lib/libimckit.dylib
/usr/lib/libimckitsa.dylib
~/Library/Application Support/com.genieoinnovation.Installer
~/Library/LaunchAgents/com.genieo.completer.download.plist
~/Library/LaunchAgents/com.genieo.completer.update.plist
If there are other items with a name that includes "Genieo" or "genieo" alongside any of those listed above, move them as well. There's no need to restart after each one. Some of these items will be absent, in which case you'll get a message that the file can't be found. Skip that item and go on to the next one.
Restart and empty the Trash. Don't try to empty the Trash until you have restarted.
Step 3
From the Safari menu bar, select
          Safari ▹ Preferences... ▹ Extensions
Uninstall any extensions you don't know you need, including ones called "Genieo" or "Omnibar," and any that have the word "Spigot" or "InstallMac" in the description. If in doubt, uninstall all extensions. Do the equivalent for the Firefox and Chrome browsers, if you use either of those.
Your web browser(s) should now be working, and you should be able to reset the home page and search engine. If not, stop here and post your results.
Make sure you don't repeat the mistake that led you to install this software. Chances are you got it from an Internet cesspit such as "Softonic" or "CNET Download." Never visit either of those sites again. You might also have downloaded it from an ad in a page on some other site. The ad has a large green button labeled "Download" or "Download Now" in white letters. The button is designed to confuse people who intend to download something else on the same page. If youever download a file that isn't obviously what you expected, delete it immediately.
You may be wondering why you didn't get a warning from Gatekeeper about installing software from an unknown developer, as you should have. The reason is that this Internet criminal has a codesigning certificate issued by Apple, which causes Gatekeeper to give the installer a pass. Apple could revoke the certificate, but as of this writing, has not done so, even though it's aware of the problem. This failure of oversight has compromised both Gatekeeper and the Developer ID program. You can't rely on Gatekeeper alone to protect you from harmful software.
Finally, be forewarned that when Genieo is mentioned on this site, the attacker sometimes shows up under the name "Genieo support." He will tell you to download a fake "uninstaller." As he intends, the uninstaller does not completely remove the malware, and is in fact malware itself.