When trying to debug a Silverlight 4 application in Visual Studio 2010 with Firefox as my browser, I am unable to hit any breakpoints. I get the message \"breakpoint will not cu
Firefox hosts silverlight (and other plugins) in a sandboxed process called plugin-helper.exe
.
Manually attach your debugger to the correct instance of this (it'll have "Silverlight" in the process type field), and you get your debugging back, and you get to keep your plugin sandboxing too.
EDIT:
Looks like someone else sick of doing this by hand and wrote an VS2010 addon to automatically attach to plugin-helper.exe
.