Jump Desktop on the PC requires Microsoft's .NET Framework 2.0 or higher. Windows XP users may not have .NET Framework installed, or in some cases the .NET Framework installation may be corrupted. Follow the steps below to fix the issue. Please note - the steps below apply only to Windows XP based machines:

To fix this we'll first uninstall all versions of .NET Framework from your PC and then install the latest version of .NET Framework from Microsoft's website:

1. Open up the Control Panel and then double click Add Remove Programs. 
2. Uninstall all versions of the .NET Framework. You may have multiple versions of .NET Framework installed on your PC please make sure you remove all versions (2.0, 3.0, 3.5) etc. 
3. Restart your PC. 
4. Next download and install the latest version of .NET framework from Microsoft's website: http://www.microsoft.com/net/download.aspx 
5. Once installation is complete try downloading and installing JumpDesktop.msi.