Infopath form not open from Sharepoint document library ?

Question

 
I have successfully submitted infopath form to sharepoint document library, it shows there. Now i try to open this form by clicking it and select open option.I am getting following error message-->
Infopath cannot open the following file:
http://testappsdev.nation.com/apps/Preventionincidents/Preventionincidents/loss prevention incidents-20121101203.xml?source...........................
The form template trying to access files and settings on your computer.Infopath cannot grant access to these files and settings because the form template is not fully trusted. For a form to run with full trust, it must be installed or digitally signed with a certificate.
How i overcome this?