Congrats on solving!
Question ... does mrooms.net mean you are hosting on MoodleRooms?
MR a 'former Moodle Partner' that was purchased by Blackboard? and that recently was sold to a technology group in UK.
MR did do core customizations and was known for running on Windows servers as opposed to the majoity/masses of on Linux.
Not trying to be 'chicken little' here ... just sayin'!
'SoS', Ken