i recently hit a weird snag when i went to change a sample application from using
virtual earth version 3 to version 4.
with doing nothing at all but changing the "v3" text in the virtual earth control reference to "v4" i suddenly got this error message:
"Sys.InvalidOperationException: Object Microsoft already exists and is not a namespace.”
my VE control reference was in my <head> tag, and as soon as I moved it within the body tag, the error went away and all is well. so there you have it -- if you are getting this error of course :-)