People running web servers are generally liable for contributory culpability, when some user breaks the law by putting the material on the server. There are legal mechanisms for relieving the server guy from this burden. The best-known mechanism is "DMCA takedown", where you publish contact information so that an offended person can serve up a proper legal claim that you are distributing material that they own copyright to. If you follow the rules, you may enjoy "safe harbor" protection against contributory liability: one of the requirements is that you have to take infringing material down. The specific requirements can depend on the nature of the liability and jurisdiction, but generally involves a "hands off" involvement where the person has no knowledge of what's going on on his server. So just disclaiming responsibility does not work. There are other more serious violations, such as distribution of child porn or transmission of top secret information.
Jurisdiction is not totally central to internet questions, and I could sue you (the server guy) in US courts, or (depending on the offense: copyright infringement of a particular item) in UK courts. Nailing this down specifically to Sweden is harder, but recall that The Pirate Bay had a whopping judgment against them.