Hi Aurian,
Myself and another lady in the TTC 1-6 Months July 2009 thread have been thinking the same about Vitex.
I'm not 100% sure if Vitex is affecting my chart as this is the first time I've mapped my temps.

FF is sending me insane, I keep changing the settings to hopefully get a true reflection of when I actually O'd.

All the best in the TTC journey....
Charlie