"Invalid regular expression" in visual-basic-mode.el

[Mathias Dahl]

I am testing Emacs CVS on Windows XP (fetched from the
nqemacs-project) and get errors in visual-basic-mode that I
did not get in 21.3. I have turned on debug-on-error and the
problem is with the following code:

 (looking-at "^.*\\_[   ]*$")

If you evaluate the above you will get the error mentioned
in the subject line.

Is this a bug in Emacs or in visual-basic-mode.el? I know a
bit of regexp myself and the example above seems valid to me.

/Mathias