Comment 49 for bug 89160

I has been solved by me.
After checking my firewall I noticed it was complaining about a syn flood when I was unable to connect to a website. In my setup at home this firewall is not really needed so I turned it off. All the problems are gone since that moment.
So, obviously Ubuntu makes my firewall thinks there is a synflood where it is just a normal TCP attempt. Next step is to check why my firewall is blocking this, but since it is build into my DSL modem, managed by my telecom provider it will be hard to correct this (my modem is a Siemens SX552 WLAN dsl modem).