Not exactly sure how to explain this -- track is 'Record' enabled and the meter is registering a signal (pulsing, if you will) but I am not supplying any input.  A&H ZED-22FX board.  All outputs are muted.  I'm using a laptop (PC).  I thought I remembered reading somewhere about this being caused by the soundcard but I can't find it and I'm not sure how to correct it.  Thank you in advance for any help. 

There are a lot of things that can cause noise in a track.
Have you gone to the A&H web site and downloaded the latest drivers for the Z-22?
In SONAR, click the Options button at the top, then Audio and make sure that the 22 is selected as both the Recording Timing Master and Playback Timing Master, or in later versions of SLE, press the P button on the computer keyboard and select it as the Recording Device and Playback Device.
Under Driver Mode, choose ASIO if it's available.