I'm getting attacked bij commoners, sailers and beggars everytime I go into the docks.
If I kill them my reputation drops tot 10.
I know this has nothing to do with my current reputation (20). What could be the problem?

Somehow you pissed them off, you might have accidentaly killed a commoner where everybody did see, but I guess than you can't have a 20 rep. Hmmm...

Perhaps he failed a pick pocket ...

I don't recall killing a commoner and I hardly ever pick a pocket so ...

Maybe an errant spell killed someone?

Usually, it is due to an area-of-effect spell that inadvertantly damaged an innocent bystander.

That is not possible either, because I have never used magic in the town (I have had no problems with the Cowled Wizards).
The weird thing is that some commoners don't actually attack, but turn hostile and than run for it.

Did you open any chests in anybody's room or house? In other words - steal something?

I did steal something in the Harpers Hold and in Mae Vaers'Guild hall an maybe somewhere else.
Is there anyway Ik can stop this, because it is pretty annoying.

Hmm, Power Word: Reload is usually pretty effective. I don't know if there is a cheat's way of fixing it though.

Control Y should kill them without damaging your rep. Hopefully, none of the plot critical characters are hostile.

I'll try this out.
Thanx.