Ok, I do not think you are hacked, exactly.
When you do a WHOIS against 81.52.249.55, you get the following:
Non-authoritative answer
Recursive queries supported by this server
Query for 55.249.52.81.in-addr.arpa type=255 class=1
52.81.in-addr.arpa SOA (Zone of Authority)
Primary NS: bow.rain.fr
Responsible person: root@bow.rain.fr
serial:2003071809
refresh:3600s (60 minutes)
retry:600s (10 minutes)
expire:2592000s (30 days)
minimum-ttl:86400s (24 hours)
Ok, so this tells you that this IP is in the range that is owned by BOO.RAIN.FR
Ok, then, who is that? Well, I am not sure. You can't do a normal WHOIS against an international domain. So, I went to www.allwhois.com and on there you can search. Basically, some French company ownes that domain.
One interesting thing is if you go to www.rain.fr, you get redirected to France Telecom website.