Checked, I can join others. It shows the message that connection cannot be established and that I should check the modem bla,bla bla.

IP ban? For what? I played W3 few times today and every time it worked and now thing like that? Can anybody help?

Your connection has been temporarily restricted from Battle.net. This restriction is realm-specific and can last up to 2 weeks.

It can happen for any of the following reasons:
- Using an invalid CD key
- Rapidly connecting and disconnecting to Battle.net
- Creating or joining numerous games within a short time period such as "Magic finding" or "Baal runs"
- By the use of "add-on programs"
- Chat channel abuse
- Failed login attempts
- In game latency caused by excessive spell effects

We are unable to lift these restrictions early or tell exactly why the restriction was placed on your connection.