Are you using some ISP-supplied software to get online, and/or some sort of firewall / browser extension? Did you commit the cardinal sin of inserting any ISP-supplied disc into your machine?
I could tell you horror stories about Wanadoo and Free.fr "drivers" here in the land of Frog. And I am sure that mentioning anything to do with BT's similar stuff that was prevalent a few years ago will make Milo feel positively ill.
