It's definitely a problem with Windows Aero. Try right-clicking your desktop and select Personalise. Then on the right you will see different themes for your Desktop. All of them are categorised by "Aero themes" and "Classic". Switch to Classic and then back to Aero.
Sometimes things get buggy, glitchy and some files get corrupted, if the above didn't help, try restarting and do the above again. To test things out, you might as well create a guest user and see if the guest user has the same problem.
Good luck