Google Toolbar does not modify the settings of your browser. It's just an add-on providing a few different features you can use while you browse. If you encounter issues, try installing the toolbar again. This way you can verify if the toolbar is the real problem. Also, you can try resetting the browser to its original settings going to Tools > Internet Options > Advanced > Reset. There will be 2 reset options and you can use them both to restore the browser to its default installation status.