error message on xml install

I used dreamweaver to create RSS feeds.
With my previous install of XAMPP they ran flawlessly.
Now with the latest update of XAMPP running I have this
error message:

> Fatal error: Call to undefined method domdocument::loadXML() in...
According to one of the members of the dreamweaver newsgroup this is the
reason:

>>domdocument::loadXML() is part of the DOM extension, which is part of
>>core PHP 5. So if you're getting that message, it sounds as though you
>>have a sick installation.

I have reinstalled the XAMPP package 4 times now and I still have the same
problem.
Of course the reason I reinstalled the Xampp package four times was because
the first
time that I installed it I placed it in the wrong folder. When I corrected
my mistake the
registry was never updated with the new path for the services on windows
vista. So I had
to hack the registry to alter the path of mySQL, and Apache to correct the
path for the services.

Now I can run my pages against the apache server and query the mySQL
database without
problem, but the rss feeds that I created fail, and in doing so the pages
stop processing and display only the code above the RSS feed. The rest is
simply cut off.

Can anyone advise me as how to proceed, or refer me to another newsgroup or
forum that may help?

thank you
Kevin