Can't view site in Internet Explorer

I've built site using the Sportal template.
www.testsitegct.niwebs.co.uk/

It works perfect in all browsers except IE. When I try to view in IE I get the following message (see attachment);
Do you want to open or save testsitegct_niwebs_co_uk.css from www.testsitegct.niwebs.co.uk ?

I'm using Joomla 2.5 and the 2.5 ver of the Sportal template.

I have tried unistalling all the modules & plugins I installed but it still wouldn't work.

I can access the back end in IE ok.

I've never come across this before so any help would be much appreciated.

Thanks
Mark

In files:

css/template_css.php
css/template_css_ie78.php

you have this line:

header("Content-type: text/css");

remove it in both of them.

Thanks Ivan, that's fixed it!

ivan.milic wrote: In files:

css/template_css.php
css/template_css_ie78.php

you have this line:

header("Content-type: text/css");

remove it in both of them.

Hello,
I have exactly the same problem, see: www.sanda.nu but i do not have header("Content-type: text/css"); i any of the above mentioned files. i am using hot flashes template.
/Thank you in advance,
/Micke

Maybe some component you are using adds false header information, or has echo.... before joomla generates it's header