Light-based effects clash

Hi all. I was wondering whether you guys might be able shed some light on a an effects issue. I've set up an exhaust-flame effect for Krzysztof Malinowski's P-40 as a LOGO light. The effect works fine. However, it interferes with the VC light. To begin with, when I activated the exhaust effect by tuning on all the lights, the VC light would turn on once but then turn off again. No VC light for the course of the flight. I therefore made a gauge folder and some XML gauge code so the exhaust effect would operate independently. The gauge worked fine and the exhaust effect worked okay, too. Although it's appearance was diminished, it's probably more realistic. However, now the VC light intermittently flickers on and off (as if there's loose wire somewhere) probably in correspondence to intermittent flashes of the exhaust effect, although it's difficult verify the association. Any ideas how I can fix this?Cheers,Matthew.