I also discovered that the debugger in Visual Studio 2005 does not work with IE8.0. I researched this on the internet and found a solution. This method does not require that you close your IE windows first.
1.Open RegEdit
2.Browse to HKEY_LOCALMACHINE -> Software -> Microsoft - > Internet Explorer - > Main
3.Add a DWord value called TabProcGrowth
4.Set the TabProcGrowth value to 0.
http://stackoverflow.com/questions/663144/why-cant-i-debug-from-visual-studio-2005-after-installing-ie8
