Editor stripping html

Hi,

Firstly sorry if this has already been posted.. i did have a look around but kept coming across bitter arguments between developers!

Ive been using CK editor with drupal for quite a while, however with the last few sites ive done ive run into this problem:

In Source mode, i enter the html code. eg:

<p class="test">Text here text here</p>

If i hit save still in source mode its all fine. If i click back out of source mode, the formatting is stipped. I click back on source to check it and it has changed to:

<p>Text here text here</p>

So everytime i want to edit the text and keep the html formatting i have to go back to all my text edit files where ive save the html and re-paste in. Which is annoying, but when i have clients who have no knowledge of html this becomes a major issue.

Any ideas???

Thankyou!