Hi
When I'm trying to use AGPS, the results are baaad. When I'm in Lublin, Poland (I would make a google maps screenshot, but I'm experiencing technical difficulties), ovi maps tell me that I'm in Szadek, near Łódź, Poland. It's central part of our country, about 250km from Lublin.
I tried supl.nokia.com and supl.google.com but no effect.
What can I do to repair it?
Thanks in advance

The first thing I would do is to try and isolate the problem: can you try one of the alternate GPS mapping programs, say, Mappero or something? If the problem goes away, then the fault must lie in Ovi maps; if not, it is something more related to the GPS data itself...

What exactly is your problem?

To use AGPS, you need to be connected to internet (via WLAN or GPRS/UMTS).
AGPS will only fetch data to show an approximate location (few 100m) and load some satellite data (almanach) to provide faster satfix for GPS.

The reason for displaying Szadek is, as you already discovered, that it is the central part of your country. This is the first location chosen by Maps, when there is no valid GPS signal.

I AM connected to WLAN

The expected outcome is being detected in Lublin
The actual outcome is that I'm being detected 250 km from where I am

my gps is also acting strange

Try the following:
shutdown your device and remove the battery for a few seconds, reinsert, boot up and try again.
Hope this helps (as it did for some of us).

There is an app called "GPSJinni" in the repository, that I think might be helpful. It provides a great deal of information on how your GPS is functioning, including the exact latitude and longitude being calculated. You can use this to see whether your GPS is coming up with a bad location (or no location at all). It may be that your location is being determined just fine, but for one reason or another, Ovi Maps is not picking it up.

I was having problems too, I recently flashed my phone and my gps wasn't working, it was showing Spain. So I changed the location to supl.google.com and now it's working fine.

Yeah, I had exactly the same problem with cell location in Poland using supl.nokia.com server. It was showing "Szadek" localisation despite I was several hundred km away from that place... Changing localisation server to supl.google.com did miracle, now it works perfectly :-) It is shame that Nokia's own server won't work as it should on their own hardware :-(

Now its working fine. I bet it was using the cached localization and first after change it used the cached one.
Thanks for all
@sylwiusz: I do agree with you. And now imagine: year 2012: you need to reflash using images from samsung.com