Right now I’m running VS.NET 2003 and Whidbey side by side for some projects that I am working on. When I popped back into VS.NET 2003 to do some ASP.NET 1.1 stuff the other day I was met with these rather daunting errors.

VS.NET output:
Auto-attach to process '[3544] aspnet_wp.exe' on machine 'XXXXX' failed. Error code 0x8013134b.
Assuming that it had something to do with the fact that I had Framework 2.0 installed, I quickly brought up ASP.NET Version Switcher. Surely enough the virtual directories for my newly created VS.NET 2003 projects were using version 2.0 of the framework. Not sure exactly why this was happening or why it was preventing the debugger from attaching, but switching framework versions seemed to do the trick. Sweet!!!