When you use Google, your IP address is detected and your query is automatically directed to the local version of Google. (That's why you'll often find UK firms near the top of the list, even though you didn't use a 'UK only' search).
The internet has suffered some major 'backbone' problems over the past few days. It seems that your ISP (or the company which supplies them with access) may have lost their normal access into the backbone. It sounds as if they're having to use a back-up plan and route all their traffic through a French proxy. This maintains your connection to the internet but fools Google into thinking that you're in France.
If checking your preferences doesn't work, I'd contact your ISP and ask them what's going on.
Chris