An administrator has installed Google Chrome on this system, and it is available for all users. The system-level Google Chrome will replace your user-level installation now.
WARNING: Backup your Google Chrome data first. You can use Chome Backup.
This was tested on Windows 7 Ultimate; it may work on Vista.
This error occurs when Google Chrome is available for all users. By default, when Google Chrome installs it is installed in the AppData folder so it does not require admin rights for installation.
Navigate to C:\Users\yourusername\AppData\Local\Google\Chrome, where you should find a folder called Application. Delete the folder, but DO NOT DELETE the user data folder!
Navigate to C:\Program Files\Google\Chrome\Application and make sure Google Chrome exists (this is the default location).
In the Windows start menu under Google Chrome, change the shortcut location to the location given in Step 2, and then you can pin the program to the taskbar.
Hopefully this will solve the issue, and you may want to run CCleaner to clean up your computer afterwards.