i have several tradfri bulbs that are all working fine. one that i bought recently ceased to work shortly after setting it up. it was flickering and obviously sending random stuff over the zigbee network, because other bulbs were losing their pairing to the base. when i unsrewed the bulb it was awfully hot. after returning and replacing the bulb i had no more problems.
it seems however, that ikea has problems with tradfri quality control.