Firefox has the ability to use the Arobat Reader plugin and it is set by default. Whenever you click on a PDF link without realizing, it will freeze your browser for about a minute before it responds correctly. If the plugin crashes, it also crashes your browser. This is really annoying and there is a very simple fix to this.
To fix it, in Firefox prss Tools and then press options and select the Downloads section. Then press the button labeld "View & Edit Actions...".
A new screen will appear listing many different file types and actions to go with the file types. Find PDF using the search box and press "Change Actions..."
A new window will appear like the one on the top of the page. Select "Open them with the default application" and press OK. Next time you open a PDF, it will launch it in Acrobat Reader.