Following the recent skin changes an active recording is not marked a red in the guide.

http://forum.team-mediaportal.com/mediaportal-releases-315/3-issues-current-oct-2010-1-2-0-trunk-builds-87856/

h4. Steps to Reproduce
Set a program that starts shortly to record (it will turn red in guide)
Wait until program starts and it will turn dark to mark current program (loosing the red)

h4. Additional Information
I am fairly sure this is a case of the current program colour taking priority of the recording colour