Run-time error 6148 in Scheduler

[chittenden]

I use the Impromptu Scheduler to generate several Impromptu reports as PDF files. The Scheduler program remains active on a PC which is left on all the time as reports run on various dates/times unattended. This past month-end some of the scheduled tasks did not complete. I decided to close and re-open the scheduler program. When I closed the program there was a scheduler error message which read "Run-time error 6148 Invalid row number" Anyone know what this means?

Thanks