Php Errors - Please Help

My shopfront is returning errors as you can see here

Warning: Cannot modify header information - headers already sent by (output started at /home/jenadmin/ in /home/jenadmin/ on line 28

My web host must have changed something as I hadn't changed anything in the code

I did have PHP 5.5 running and I have just upgraded to 5.6 in the hope of fixing it, but to no avail

Can anyone please let me know how I can fix this?

I have version 4.2.3 of cs cart

Please make sure that there are no empty lines before the tag in the index.php file

Hi, I have checked that - thanks.

Does anyone have any other suggestions for me?