Need help converting file types with Camtasia

Hi. I badly need help as I need to finish my project as soon as possible. I have .camproj files saved in my Windows Vista PC. I used Camtasia Studio of TechSmith.com. I am almost done with the project but today, I can't seem to access those files. I keep getting an error stating that Camtasia Studio doesn't support the file type. On the properties of the file that I cannot access, the file type is saved as .camproj~. Does anyone encounter the same problem? How did you manage to resolve it? If none, how can I convert those file type to the correct file needed? It was working well for the past few days but this morning, I did some backup to my files and put it on my external HDD. I remembered the Camtasia Studio is empty and I wasn't able to back up those files for whatever reason it is. And then I performed a defragmentation for 8 hours. Is there a possibility that the problem is connected to it? Kindly please help me. Thanks.
