auto sandbox dialog box hangs!

i use primo pdf to convert webpages to pdf format. today after installing avast6, while i opened primopdf, a dialog box popped asking whether it can run it in auto sandbox… no matter what option i select ,after clicking OK button, the dialog box still remains and doesnt run the prog either normally or in sandboxed environment!! finally closed it in task manager and decided to disable autosandbox and try to use primopdf, and to my surprise, Avast gui was blank!!! (as in the img attached) and even avast gui neither closes/minimises/maximises… have to force close it using task manager…help out with solutions please