CP plugin disables codehighlighting plugins

I have installed CustomProperties for joomla 1.7. After that all code highlighting plugins doesn't work when I read the articles.
I tried next plugins:
1. higlight_code
2. Content - Code HighLight
3. Content - CodeCitation

When I disabled Content - Custom Properties Tags Plugin the code highlighting plugin is work OK.

We think the issue could be caused by Custom Properties' default settings, that strip the "<pre>" tags from articles.
Please add '<pre>' to Allowed tags param in Custom Properties configuration.
(We've been able to have code highlighted with Geshi and CodeCitation)

It didn't help. I have add the to the Allowed HTML tags. But Code highlight doesn't work.

P.S. I use now CodeCitation on the site.

We were actually able to have articles with proper syntax highlighting AND CPtags on our public demo server (demo1720.solidsystem.it). Since it's reloaded every our we took a screenshot. We followed our own advice to add '<pre>'.
We found that the editor plays tricks on you (escaping chars, adding tags, etc) therefor we opted to edit articles with no WYSIWYG editor. That helped too.
Please find herewith attached the screenshot and the content of the 2 articles: 1 for Geshi and the other for Code Citation.
If the problem persists then chances are that there's some kind of conflict between plugins. We may need to take a look at your installation.

I don't use WYSIWYG for now. Adding <pre> doesn't help.
I can send Akeeba backup file to you for testing. Where do I shood to email?
P.S. One more. If I activate CP plugin and CodeCitation then in BlogLayout they works fine, but if I open any article then CodeCitation doesn't work. If I disable CPplugin CodeCitation works fine in both times.

The test you carried out will likely speed up troubleshooting.
We'll let you know where to send the backup.