[eluser]WanWizard[/eluser]
Guess your webserver authentication needs to be improved...
What server is your webserver running on? And do you have (commandline) access to it? If you do, you could use a network analyser to check the traffic. If not, do you have a firewall or router in front of the webserver that you can use to analyse the traffic.
The IP belongs to the range of Belgian ISP Telenet, geo located somewhere south of Antwerp.