I have that problem too paulie but to be honest for small amount of times that it does it im not too bothered about it, simple fix when you switch them off and on again, next time i think i'd go brighter thoughI had HIDSDIRECT 35w D2S 6000K Ultra HID kit on my car, ..but every now and again one of the ballasts would fail. They are not 100% Canbus compatible as they say they are. They use older technology (Generation III ballasts) and are prone to failure. I've bought myself a set from Xenonshop.co.uk, a 55W kit, so the Canbus just detects the same as it would when the standard halogens are in, ..it's when you put certain 35W HID kits in that the Canbus detects the lower power draw and shuts the bulb down to protect the electrics, as it thinks the bulb is out. I've had the new kit in for a couple of months now and not had a single problem with them. They are classed as Generation IV ballasts, they run at a lower constant power than the older HID kits too, so don't drain so much from the car battery.