Please check that your graphics card drivers are to date. Graphics driver issues are the most common cause when experiencing crashing with CrazyTalk 7.Also try running "Windows Update" to ensure your system is fully updated.
If this fails to help, please contact Technical Support using the link below. They will be able to advise you further. Do make sure you supply them your dxdiag.txt so they can check for any obvious issues.
http://www.reallusion.com/CustomerSupport/User/QForm.aspx
Thanks.