Please download the .NET 3.0 installer from Microsoft, install it, and then try to reinstall Jing.
To download Microsoft .Net 3.0, please visit the Microsoft Download Center, or obtain these updates through Windows Update by performing a custom update.
If you continue to have problems with your install, please Contact Support.
Jing also requires the .NET Framework 3.5, if you do not have .NET 3.5, please see this article:
Jing crashes at startup of XP, Vista, or Windows 7