I have Mac OS X, using boot camp i installed windows 7. installation was successful but when i try to select to boot back to mac os x via boot camp from Windows 7 control panel, its saying "You may not have privileges to change the startup disk..."

from the boot camp control panel, highlighted "Macintosh HD Mac OS X", click on Restart button or click OK or click Apply buttons gave me "An error occurred while trying to change the startup disk. You may not have privileges to change the startup disk. Make sure you have administrative privileges and try again."

Im logged in to Windows 7 as admin thou but still giving me the above message.

i rebooted & the option key does not give me option to boot to Mac instead gives me a screen with lock then below is a blank field then a right arrow on the right side, i normally hit the power button from this screen

please help

thx