Try this... right or control click a PDF file you have stored on the drive then click Get Info.
Select Adobe from the pop up menu next to: Open with
Then click: Change All
You can also try deleting the PDF Browser Plug-in from /Library/Internet Plug-Ins.
Hi Carolyn, thanks for trying to help.
I did what you suggested, but no joy! It is a funny file that says: @ on the icon on my desktop.
It still opens by quicktime if I click on the desktop, but if I drag it to the adobe icon in the dock it opens a dialogue box that says it can't open this kind of file.
I checked the library, but there's no plugins listed.