Neither have I. In fact I never had that error at all. Have you both reformatted the cards before each new recording ?
FWIW I am still running FW 1.4.3 ...
I usually reformat, but do not always remember to. I think the Kingston is more sensitive to needing an occasional reformatting. My 5GB Seagate never required it, it made absolutely no difference, and the Sandisc I use currently does not seem to require or especially react if I reformat or not.. The message I get with the Kingston 4GB, is no longer an issue because it records fine, but strange that it happens. I have a 2GB Kingston, and I do not get the message with that CF card. Now I tend to use the Kingston 4GB in my Camera or Tascam, because of that one extra button push required, but I would not hesitate to use it if I needed it.
Strange that not everyone gets that message. I am running the newest 1.4.5, which I think is the best firmware to date.