page encoding to greek

Hi there,
I have a page which has english characters. for example...CategoryID.What i do
is that i translate this into the greek version which is "?????????". While i
work in Dreamweaver everything seems fine but when i finish my job and close
the file, and try to reopen it again then my greek letters become some kind of
comination of symbols and letters i dont understand, crap.
My encoding on the page is 8859-7 for the greek alphabet.
I try to change the panel Preferences on Dreamweaver but every time i
translate and close and reopen my greeks are gone and i have to do all the work
from the start.

What is wrong can anyone give me a hint??

thank u