The .NET Framework version 4.0 was installed after QuickTest Professional was installed which is the possible issue for this QTP behavior.
When you desire to work on .NET 4.0, then itís better to firstly install this before the installation of QuickTest Professional. If .NET 4.0 is installed after QuickTest, then you need to register following two .NET DLL files as per the procedure given below.:
1. If working on a 64 bit operating system, you will be required to install patch QTP_00709.
2. Open a command prompt (Start > Run > type "cmd" > Click "Ok")
3. Navigate to GlobalAssemblyCacheNet4
4. Run the following two commands:
1. ....binGACRegUtil4x86.exe -i Mercury.QTP.Agent.dll
2. ....binGACRegUtil4x86.exe -i Mercury.QTP.WpfAgent.dll
The above mentioned steps should fix this issue.
However, just in case if it doesnít happen, we would recommend to carryout clean uninstalling of HP QuickTest Professional.
(We will be posting detailed steps to do a clean uninstall very soon in an upcoming article on QTP)