index.php error

[#1]

why am I still getting this occasionally using Firefox 3

[#2]

Dunno.  But I see it occasionally  too 
I've not discovered any pattern as to when or why it happens.  Most times, it just "goes away", but infrequently I have to close and restart FF?  Was on 3.0.3 till this morning - now on 3.0.4
Maurice

[#3]

Just happened on 3.0.4 but happened on the earlier versions as well

[#4]

Would suspect it's the browser misinterpreting something in the HTTP response, I see it a lot on various other sites I use - including Tesco's online shopping the last time I was trying to order something
If you can see the HTTP headers when it happens, through Firebug or something, I'd be interested to see them.

[#5]

Colin,
Have now installed firebug.
Can you give some instructions as to what you want me to do.

[#6]

If you enable the Net tab for the site, you should be able to see each element of the page loading. If the page presents you with that, you need to bring up Firebug and look at the index.php bit for the response headers (by clicking the > next to it and choosing the Headers tab. It'll be omething like:

Response Headers
Date	Sun, 16 Nov 2008 10:39:17 GMT
Server	Apache
Expires	Mon, 26 Jul 1997 05:00:00 GMT
Cache-Control	private
Pragma	no-cache
Last-Modified	Sun, 16 Nov 2008 10:39:17 GMT
Content-Encoding	gzip
Vary	Accept-Encoding
Keep-Alive	timeout=15
Connection	Keep-Alive
Transfer-Encoding	chunked
Content-Type	text/html; charset=ISO-8859-1