Internal Server Error 500 when publishing POST with WP 2.8

when I publish a specific article with this script:
/wp/wp-admin/post.php

I get this error

[QUOTE]
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, +++@+++.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
[/QUOTE]

In the server log I found this:
[QUOTE]
Resource Logs
Users may use this screen to identify processes which may have been modified or terminated by our automated process monitoring system.
Date Action Process Reason
Jun 22 2009 3:24:28 KILL php5.cgi’/’php5.cgi Memory hog PHP
[/QUOTE]

Now the article is a press release copied from a PDF document. Nothing special. I published more complex and longer articles. But each time I PUBLISH or UPGRADE I get the very same problem. I had this kind of behavior many releases ago and I thought it was something of the past.

I already search the forum but although there are similar issues reported by other users I didn’t find anything 2.8 specific or any solving hints.

I am using WP 2.8 and several plugins.

Any help appreciated.

Thanks
Max