Ok, i give up.... I thought i knew how to doit, but I don't.

I'm trying to export video in Premier PRO CS4

Originaly I have 24p video, I'm using cineform NeoHD...
I need it in PAL SD.
I have these settings:
- Format: MPEG2
- Presete: Custom (Based on DV PAL HQ)
- Codec MainConcept MPEG video
- Quality: 5
- TV stand.: PAL
- WxH: 720x576
- fps: 25
- field Order Upper
- Pix.Asp.Ratio: Widescreen 16:9
- Profile: Main
- Level: Main
- Bitrate enc.: VRB, 1Pass
- min 2,5; targ. 4,2; max: 6
- GPS SEt,; M Frames 3, N Frames 12, Closed GOP every: 0; unchecked Automatic GOP Placement

My sequence is set to AVCHD. 23,976...

I don't know if there is anything else relevant.

I tried with - field Order lower - nothing better...also M Frames 2, nothing.

Try mpeg2-dvd format and fields set to none for 25p if you want progressive.
Title of the post is somewhat confusing: going from ntsc to pal?

For best results you should first render out to a 24p file - prefereably something intraframe and not too lossy. Then open a new 25p project. Import the 24p rendered file and re-interpret it as 25p. Then drop it on the timeline and render out to mpeg2 PAL.

If you render a 24p timeline straight to 25p, you will get blended/duplicated frames and playback will not be as smooth. If you are only making the movie for PAL markets, then the best way to do it is to re-interpret all of your source files and work on a 25p timeline.

What camera are you shooting with and why are you using 24p when you want PAL?

There are two more issues with your encoding settings:

1. VBR encoding should always be done in 2 passes, not 1.
2. Your target bitrate is really low. Did you use a Bitrate Calculator (http://www.videohelp.com/calc.htm) to check if you can make it higher? Really, you should avoid going lower than 6000 kbits target/8500 kbits max bitrate for good quality if possible.
You don't mention how you are encoding the audio, but if you are encoding in PCM audio you could switch to AC3 and gain some more room for the video bitrate.
If you cannot go higher than 4200, you might think about encoding an intermediate out of PP, and then doing the dvd encoding with a better encoder than the built-in Mainconcept one which is not really good enough to deal with such low bitrates. "HC Encoder" is a great free mpeg2 encoder. "TMPGEnc" is another good popular choice, and relatively cheap.