Debug with Visual Studio 2005 and IE8

IE 8 has a feature called Loosely-Coupled Internet Explorer (LCIE) which results in IE running across multiple processes.
http://www.microsoft.com/windows/internet-explorer/beta/readiness/developers-existing.aspx#lcie

Older versions of the Visual Studio Debugger get confused by this and cannot figure out how to attach to the correct process. You can work around this by disabling the process growth feature of LCIE. Here's how:

1) Open RegEdit
2) Browse to HKEY_LOCALMACHINE -> SOFTWARE -> Microsoft -> Internet Explorer -> Main
3) Add a dword under this key called TabProcGrowth
4) Set TabProcGrowth to 0

Since you are running on Windows Server 2003, this is all you should need to do. If you run into the same problem on Vista or newer, you will also need to turn off protected mode.

Disabling script debugging in VS 2008

Disable all script debugging

Open a new command prompt (start->run, cmd.exe). If you are on a 64-bit computer this needs to be a 32-bit prompt (start->run, c:\windows\syswow64\cmd.exe)
reg add HKLM\SOFTWARE\Microsoft\VisualStudio\9.0\AD7Metrics\Engine\{F200A7E7-DEA5-11D0-B854-00A0244A1DE2} /v ProgramProvider /d {4FF9DEF4-8922-4D02-9379-3FFA64D1D639} /f

(re)enable all script debugging

reg add HKLM\SOFTWARE\Microsoft\VisualStudio\9.0\AD7Metrics\Engine\{F200A7E7-DEA5-11D0-B854-00A0244A1DE2} /v ProgramProvider /d {170EC3FC-4E80-40AB-A85A-55900C7C70DE} /f