Error 1001 The specified service does not exist as an installed service

If you run into this problem trying to uninstall an application that includes as service like JTB FlexReport this post might help.

Error 1001. An exception occurred while uninstalling. This exception will be ignored and the uninstall will continue. However the application might not be fully uninstalled after the uninstall is complete. --> The specified service does not exist as an installed service

Still the uninstallation rolls back.

Try repair of the installation and then uninstall again.

Another workaround can be to manually install the service like this:
"C:\Windows\Microsoft.NET\Framework\v4.0.30319\InstallUtil.exe" "C:\Program Files\JTB World\JTB FlexReport\JTBFlexServ.exe"
alternatively depending on what .NET Framework version you have installed:
"C:\Windows\Microsoft.NET\Framework\v2.0.50727\InstallUtil.exe" "C:\Program Files\JTB World\JTB FlexReport\JTBFlexServ.exe"

Other indications of this problem can be seen in the Event Viewer.

“The description for Event ID 11001 from source MsiInstaller cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event:

Product: JTB FlexReport Core Service -- Error 1001. Error 1001. An exception occurred while uninstalling. This exception will be ignored and the uninstall will continue. However, the application might not be fully uninstalled after the uninstall is complete. --> The specified service does not exist as an installed service (NULL) (NULL) (NULL) (NULL) (NULL) the message resource is present but the message is not found in the string/message table”

Followed by this Information Event ID 11725: Product: JTB FlexReport Core Service -- Removal failed.

If uninstalling still fails try msizap. It's an unsupported utility that lets you browse and remove stuff from the MSI registry. It won't actually uninstall, just clean things up.
Search for MsiZap.exe on  http://www.microsoft.com or at http://msdn.microsoft.com/en-us/library/aa370523.aspx

See also Error 1001. The specified service already exists