Hmm this isnt the host!!
I guess its something like
<iframe> ashfdashfoah </iframe>
Or script=java injected into your page..
First question.. Does your host use cPanel?
2nd have you asked your host to check the raw access log
3rd: change your password to a random one of numbers and characters
4th: Does your host has FontPage extensions enabled?
5th: Is there a url / ip in the code?
6th: Who is the host
7th: whats your domain
Do not move hosts yet. Theres no point in running as it may happen as your domain could of just be randomly attacked - if you are *desperate* to move host - maybe I / we can help:
www.bionic-hosting.co.uk