Unwanted text entered automatically

I am trying to use CKEditor to replace KTML in a bespoke CMS. I have installed the files on the server and added the editor to the relevant pages. However, there is a major problem with extraneous text entered by the editor into the editing textarea. I have used FCKEditor on other sites for years with no problems.

Specifically :

1. Starting from a blank textarea, if I look at 'Source' I see the following -
<p>
&nbsp;</p>
<div firebugversion="1.5.2" id="_firebugConsole" style="display: none;">
&nbsp;</div>
<br />

2. If I open a textarea which already contains information (from the database) the editor adds at the end -
<p>
&quot;&gt;</p>
This seems to happen everytime it is reopened so I end up with a string of these at the end.

3. There also seems to be something wrong with the list function. Clicking the 'unordered list' button inserts the <li> tags but with no containing <ul> tags.

4. I copied some HTML code from another page with a list enclosed in a div. Both the div and the <ul> tags have IDs which are referenced in some javascript. If I save and then reopen the page the div has disappeared.

These are the issues I have identified so far but are enough that CKEditor is unusable. I can't believe that so many major companies can be using it with similar problems so there must be a solution. I have posted previously in the forum (http://cksource.com/forums/viewtopic.php?f=6&t=18752) but have had no response. Is this a bug or have I done something wrong?

Any advice appreciated.
Mike Davies