Win98 and DW file associations

I have recently installed DW MX. When opening htm, html, php or asp files from a browser they were opened in DW not in the browser. I have tried changing file types via Windows Explorer and configuring it so a different program is associated with editing as opposed to Opening.

I tried editing MMdocumentTypes.xml in Notepad but had to put it back to its original. I deleted a file association type for phpfile in the registry becase I couldn't edit or make a new asociation for php.

Anyway, now things work as I want EXCEPT every time I start DW I get a pop-up window which contains:

"The document type '' will not be added becuase it uses a file extension that is already associated with a prior document type." There is an OK button.

In the single quotes is 'html', then when I press OK the same message comes up with 'javascript'. And so on for ALL the file types. Then it goes thru list 2 more times. I have to press the OK button about 30 times to start DW.

What do I do? Is a reinstall needed? Is there something wrong with the registry that I can fix.

My search results on the Web have all produced near misses.

Thanks in advance for any help/suggestions.