Amir,
This is most likely an issue with your graphics card/driver or an incomplete installation. Please open a support request at http://www.ptc.com/go/academic-support and someone from the support team will contact you.
Be sure to include information about the edition and build code of Creo that you are trying to install. Also any change you have made that may have caused it to stop working (maybe you updated or changed your graphics driver for example).
Regards,
Adam
