This issue can be easily solved without having to disabling anti-aliasing . Thanks to the user "TexasRanger" who showed the right method to solve this, in the bugs section of launchpad.net, this issue can be easily solved by doing these few easy steps:
Run this command in the terminal; "sudo dpkg-reconfigure fontconfig-config" then select "Autohinter", "Always" (for subpixel rendering on LCD display), and "No" for Enable bitmapped fonts. Then, change in System/Preferences/Appearance/Fonts to "Subpixel" smoothing. Viola! Problem solved.
Now, something that "TexasRanger" forgot to mention was that, by enabling subpixel smoothing for the LCD display, fonts get bigger by enabling bold textures to them, so what you do to change that, right there in the fonts tab of the appearance menu, just below subpixel smoothing, you will see the "Details" button, just click it and it will open up another menu, now in the top left corner of the menu you will see an option to change the dots per inch values, just keep lowering the values until you get to the right size for the system fonts.
This problem might show as solved, but was probably solved by using the wrong/less convenient procedures. These few steps will allow you to see the Oo menu letters without having to disable anti-aliasing or without having to change the value of it. Hope it helped
