Scorch Plugin does not work in 4.0 Beta even when installed. Why?
Scorch plugin for reading Sibelius software music files does not work in 4.0 Beta. A page where this is accessed is http://www.musicservices.caecilian.com/TypesettingandArrangingSamples.html
Every time Firefox opened
== 4.0 Beta was installed. Previous versions of Firefox have been no problem.
That plugin might need to be updated to work with Firefox 4. You might want to report that issue to the developer of that plugin, and tell them they have 4 to 5 months to fix it before Firefox 4 is released.