Help - Anybody Successfully done Effects with Womble MPEG-VCR Software?

I'm having problems adding a fade effect to the beginning of my video with Womble MPEG-VCR and hope somebody may be able to tell me where I'm going wrong. This is how I am proccessing my video:

1) Encode the footage to my hard drive from DVD to an MPEG file using TMPGEnc DVD Author 1.6.

2) Open the MPEG in Womble and trim unwanted footage and insert a begging fade at the start of the video.

3) Saving the file as MPEG-2 Program Stream (PS)

This is where my problem starts. My edited MPEG saved with womble is now unplayable in Windows Media Player as it doesn't recognise the Codec and just freezes up when it starts to play the video. However if I just trim the video and don't add any effects like fade or wipe there doesn't seem to be a problem.

I've even tried to import the edited MPEG back into TMPGEnc DVD Author but it either doesn't recognise the file or outputs to a VOB file that is unstable and jittery.

Do I need to do something extra to the MPEG file if I am adding an effect such as Wipe or Fade?

Also does editing with Womble loose any quality in the MPEG file and subsiquent DVD I intend to create?

Thanks for any help in advance

Chris