Page corruption

Installed Drupal 5 on Fedora Core 6, Apache 2, PHP 5.1.6, Postgres 8.1 (Unicode database for drupal).

After installing - all seemed fine in Firefox for 3 or 4 days. But I noticed intermittently in Internet Explorer (Latest) that the page would be corrupt with what looked like utf8 characters gone wrong.
This would happen intermittently when viewing different drupal pages in IE, but Firefox always seemed fine (Installed fckeditor, imce and imce gallery, image and ImageMagick - where all working fine) - until 4 days had passed.
Firefox started showing exactly the same corruption, but not intermittently - all the time, and the same now with IE. All pages produce the same result - so can't get into the admin side.
It's running without 'friendly urls' - no monkeying done with http conf.
When I look at Firefox > View > Character Encoding it says it's Unicode UTF8.

I've put a screen shot (sorry - this test machine is internal) at http://www.lusu.co.uk/downloads/testtraining/drupalcorruption.jp
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Following this I decided to try on a completely different host located elsewhere - again Drupal 5.1 but this time using a MySQL 4.10a

Following this I decided to try on a completely different host located elsewherer - not inside the origanisation (I wanted to rule out any possible University webcache issues) - running Apache2, same kind of config as above but MySQL 4.10a (utf8 general ci database).

Again has been working fine both in Firefox, IE (This time IE 6) - but only after about an hour - without configuration changes, starting to see the same page corruption behaviour as above in Internet Explorer. I noticed on one occasion, when I attempted to view the home page , a download dialog appeared for IE - on the next attempt the page appeared badly corrupted.
To try to rule out upload images as an issue, I made sure the front page only contained text - no images - by administering through Firefox.

I've attached a screenshot of the page corruption, but you can also go to this host at:

http://sanctuary.j2ee-dev.org.uk/ (The corruption is appearing at this stage in IE6 after I've refreshed the page a few times with ctril + F5)

And also, to see a PHP into page for this server - http://sanctuary.j2ee-dev.org.uk/infophp.php

Thanks