Thanx Jazzman
No the problem was an un supported mpeg2 decoder. With some help from daveml - i got the TMPGEnc to open the MPEG2 files and have cut them successfully.
However - i have another problem - after the cutting process - the output file looses about 7-9 seconds of sound, at the end of the output clip.
Is this an encoder problem ?
Can anyone suggest which encoders / decoders work best with TMPGEnc - that doesnt result in a loss of sound at the end of the clip ?
If not - what other MPEG2 Editors would you recommend ?