Many of my pages (forum pages and pages which have forum SSI) are not indexed correctly by Google. Although they use Windows-1253, Google forces ISO-8859-1 encoding in its indexing and its cache. I have checked sites using the same forum software (SMF) and this does not appear to happen.

To test this please check (make sure you add the cache: bit as it is not linked and perform the search in google's search box)

cache:http://www.translatum.gr

and cache:http://www.translatum.gr/forum/index.php

and compare with

cache:http://www.cyprusgreens.org/neoi/index.php

In www.translatum.gr and http://www.translatum.gr/forum/index.php cache ISO-8859-1 appears in the google cache header; something which does not apply to the cache:http://www.cyprusgreens.org/neoi/index.php site. The funniest bit is that in some of my forum posts, Google gets the encoding right! (For example cache:http://www.translatum.gr/forum/index...ic,1302.0.html )

MSN does not appear to have a problem with these pages. Any ideas?

Where's the problem ?

It's only the cache view that sets the encoding. It will have NO effect on indexing, NO effect on your results and NO effect on users viewing the page.
The number of users looking at the cache view will vary between 0 and 1 (that will be you)

The problem is that the Greek words are not indexed properly as they are displayed as extended ASCII characters rather than Greek and hence no search results come up with these words.

For example they appear like this: Óõíþíõìá ãéá ôçí êáôóßêá óôç äéÜëåêôï ôçò ÊñÞôçò. To see how it affects search results try this search

http://www.google.com/search?num=100...22&btnG=Search

The extended ASCII characters you see are incorrectly indexed Greek characters.

I only mentioned cache as it gave me some clue as to why Greek characters were not displayed correctly. It was thoroughly tested before I made this post. I apologise if I was not clear enough.

the issue is that the results pages use UTF-8 for character encoding, so they are probably indexed correctly, but not displayed correctly. I would guess at this being because the search is in english.

What happens when you search using the Greek characters? does the encoding change to match the language used ?
does Google.gr have a "only in Greek" option ?