The problem is not Vista, but wxWidgets.
We use wxFilename::Normalize() to normalize the filename (remove unnecessary "..", expand environment-variables, etc. ).
wxWidgets interpretes $-signs as begin of an env-var, except for $-signs prepended by a "\". These $-signs are taken literally, but the "\" is stripped, because wxWidgets believes it's an escape-character.
C:\Users\$@muel Lee\Documents\a\main.cpp
C:\Users$@muel Lee\Documents\a\main.cpp
this path does not exist.
As workaround you should place these files in another directory and not in your User-directory (I guess changing the username is not an alternative).
The same issue makes it (most likely) impossible to open your project from the windows-explorer (but this might depend on the version of C::B), with the message that the project-file does not exist.