After upgrading mysql to verison 4.1.16 my swedish characters have stoped working.

Here is an example from a forum of mine:
"Här är mailet som har gått ut till er alla...."
where you can see that åäö doesn't work.

Can someday please help me.

Seems to be that the upgrade reset character coding to UTF-8 somewhere -- seems that UTF-8 wil be the standard in some future thuogh it is quite still impractical in most environments, especially when you want to exchange plain text files with a Windows system. If you use ISO-8859-1 (which I would recommend) then UTF-8-encoded text will typically show up like your example. Many Linux dists (and maybe other software) seem to try to promote UTF-8 by including it as the system default. You may have to reinstall the system if you do not change this at the very first chance, since it affects so many, many configuration points.

Now, could UTF-8 be similarly introduced by a new Mysql default setting? Cold probably be reset to ISO, else re-upgrade(?).

Just a guess!

P.S. I don't dislike world standards like UTF-8, just that everybody isn't actually ready for that yet! With everybody using it, promoted by vendors and with useful text editing software available, it would be great!