I had one like that about a month or so ago. The only difference was that the heat only cycled up to the point of ignition and then started over. The vent fan would start, then the starter would glow, then it would stop, and then start the cylce over again. Weird to see. The technician that came while I was there said it was a board at the furnace as Jim indicated it might be. The unit I saw was in the attic and who knows how long it had been doing that. I knew something was up as soon as I pulled the stairs down because the vent fan started just as I opened the attic.