More than likely a graphics error. What graphics card do you have? Most ATI cards dont get on with maya. If its important you can get hot fixes from the autodesk website and see if they help, or/and update or roll back your graphics card driver.
I know that ATI's previous version (11.11 I think) gave me graphical problems that older versions didn't in that it would render specular effects in a game as colourful noise, haven't checked since updating today to 11.12
It's your graphics card not handling Maya too well. Possibly due to overheating / overuse and also a full hard-drive. I suggest you dowload the latest graphic card drivers, switch the windows GUI to 'classic', clean up and defrag your hard-drive, periodically switch off your computer too cool it.