The flourescent light fixture in my kitchen has started to light differently.... can you help?

The flourescent light fixture in my kitchen has started to light differently. When i flip the switch, both bulbs seem to only illuminate to a fraction of their usual brightness. I've noticed that if i flip the switch off and on a number of times, sometimes the light will "catch" at full illumination and will stay that way until I turn the light off later, but then it's back to it's same old tricks... any thoughts?