Tashi - 11:34 am on Jul 9, 2010 (gmt 0)
I had the same problem once, the contact information in my Adsense account was changed so I thought the Adsense account was hacked.
Turns out it was my Adwords account that was hacked. When the contact information in your Adwords account changes, it changes in your Adsense account as well.
Contact Adwords support if your Adwords account is hacked as well, they respond quickly and will solve the matter in no time. Adsense support never responded to my mails...