403 Error after login

I’m not able to login to one of my blogs from my own IP-address since yesterday. After entering my user name and password, it throws a 403 error. I checked my Bad Bahaviour table and removed all rows with my IP address in it, but it still doesn’t work. My other WP installations work fine, though. It’s only one site that doesn’t accept my IP address. From another IP address, I’m able to login. I’m afraid I have a static IP address. Has anyone had the same problem and knows how to solve it? Thanks in advance ??