"The breakpoint will not currently be hit. No symbols have
been loaded for this document." Webgarden can cause it
too.
Changing windows 2003 server webgarden setting from the
default of 1 will cause new w3wp.exe for every debug
session. This situation apparently confuse visual studio
and VS don't know which process to attach to. Setting
webgarden value back to 1 solves this issue.