There may be occasions when the CatTools appears to be running, the scheduler is on, but no activities are running.
A look at the infolog file would probably show that an activity appears to be hung up and has not terminated. This may be caused by a logic loop or communications hanging up where CatTools cannot detect a timeout. Normally this is not something that happens every time, but may happen due to a glitch.
There is a setting on the Misc tab in the CatTools Setup that might be useful in allowing CatTools to continue running productively after such an occurrence. This allows you to forcibly terminate an orphaned activity after waiting for a set number of minutes. CatTools attempts to recover and resume scheduling activities afterwards.
You should normally leave the setting at 0 unless there is a problem so that you do not forcibly terminate an activity that takes a long time to run, but runs successfully to conclusion.
Another cause of this problem may be due to a permissions issue on the DCOM component.
To verify this as a cause, check your Info Log for the following message:
"Problem starting CatTools_Client instance #1. Error:70: Permission denied"