Vidalia torrc editor is confused by # comments
If you use Vidalia to edit any torrc (including a pre-existing default torrc) that contains a hash-introduced comment on the same line with an option setting, like
SocksPort 9050 # this is the port that applications connect on
then you get an error like
Unacceptable option value: Int keyword 'SocksPort 9050 # this is the port that applications connect on' is malformed or out of bounds.
because Vidalia tried to validate the torrc and didn't realize that the comment was a comment. However, this doesn't seem to confuse Tor itself, so there's a gap between Vidalia's notion of torrc syntax and Tor's notion.