I used adsense a while ago and I've just come back and set it up on a new site I'm developing. I must say I'm less than impressed. First there's the new leaderboard format that only shows 3 ads instead of 4 and cuts off the ends because ads are too long. Also many ads shown don't seem at all relevant (I keep getting ones for used cars on a site that sells musical instruments). But most bizarrely I regularly get ads in French - I'm in Australia, my customer base is in Australia, there are no French words on my site and I have no idea what is triggering this. It's not just me - others have mentioned it as well. I've tried all the solutions I can find but it's still happening. I'm just about ready to dump adsense altogether as it's really not doing much of relevance on my site.
I guess the general question everyone would like to ask would be, can we see the site? That would be helpful. Sometimes sites do not get well targeted ads simply because the keywords are covering a large amounts of topics on the same page (like news and cars or politics and weather, etc.). Normally, with the time, ads adjust to the content of your page perfectly. It may take 3-4 days. Maybe that's the cause of ill targeted ads as well.
your content/ keywords may be in french language. Clean coding your site then see you ad will turn in English.