Cannot debug ASP.NET in Visual Studio

Today I stumbled upon a curious bug while developing some ASP.NET code using Visual Studio 2005: the debugger didn't work. What "didn't work" means? It completely ignored the breakpoints within the code.

After messing around with this issue for a while, I discovered that the issue is actually with IE8 (?!). If there was an instance of IE8 running prior to the debugging process, the breakpoints will be ignored.

Solution: close the IE8 window, and press F5 again in Visual Studio. Viola, now the breakpoints break.