Why does F10 (continue) in Visual Studio not work?

Scenario:

I'm debugging a (web) project in Visual Studio 2008. It is breaking and the first break point only, and thereafter when i hit F10 it ignores and subsequent break points and runs all the way through. Why is this happening? Couple of pointers before we discuss the solution

• I have tried 'clean solution'.
• Other breakpoints sometimes(!) skipped, even in the same method
• Make sure that you're in Debug mode not in Release.
• There could be an exception while executing the instruction in question. Try enabling all exceptions to break into debugger and check.

The solution may be:

Tools -> Options -> Debugging -> General -> Un-check off Enable Just My Code.