I noticed this on windows XP *only*, so it feels like a bug somehow:

After changing the title of a patch to "MuModule: player # 1"
with a [patcher MuModule: player # 1( message to
object thispatcher, it is impossible to save nor to "save as…".
due to the colon character.
The thing is that when changing the title of a patcher this way,
the proposed filename in the save dialog is the title of the patch.

On windows, it seems that Max refuses to open a save dialog
with a filename containing a colon.
The Max windows print "Error in save dialog!"

On Mac OSX the colon is automatically replaced in the save window by a dash.
Maybe this could be fixed to have the same behaviour on windows?