Hi Clara,
It would certainly be worth uninstalling and performing a clean install again. Also do check that your computer is fully updated.
In Windows 7 you can do this by clicking Start > All Programs > Windows Update > Check For updates. In Windows 8 go to the Start Screen and type Windows Update. Then select "Check For Update" from the search list.
You should also try updating your graphics drivers. Check on your computer manufacturers website to find them or directly from Nvidia, AMD or Intel depending on the make of graphics you are using.
If you still have problems after that, please contact our Technical Support department using the link below. They should be able to help you resolve the issue.
http://www.reallusion.com/CustomerSupport/User/QForm.aspx
Peter
Forum Administrator
www.reallusion.com