Interlacing produces stairway-effect? How to get rid of 50i?

[faultiersid]

Hi everybody. I've got a Pal GH13, recording in 50i. When i put the files in AE or Premiere CS5, I see some "stairway-effects" on diagonal lines. From what does this come from? They are noticeable even at 50%.
In the attachment is an outrendered frame in PNG format, look at the lower strings of the guitar. actually, the original AVCHD looks even worse, I think the rendering to PNG made it a bit better.

Is this normal, since the GH1 does line-skipping, or does it come from the 50i wrapper?

Also, how should I treat the interlaced wrapper in CS5? Shall I simply interpret the footage as 25p, or do I have to do an interlacing process?
I see no difference when I set the field order to progressive in the "Interpret footage"-window.


edit/ hm, the png-attachment has been scaled down, I'll upload the image somewhere else in fullres.

here it is: http://img829.imageshack.us/i/000280000806.png

 

[l.breyers]

You need to do pulldown removal. Dont rely on adobes products to do anything like that, except while working as a quick preview.