Nikon and IBM have discovered an incompatibility between a certain revision of the latest IBM Microdrive and the Nikon D1X. The incompatibility prevents the affected Microdrive models from functioning at all in Nikon's latest digital SLR - the camera's top LCD will blink "CHA", and the counter will read "0".
The problem, which manifests itself only with the most recent production of the 512MB and 1GB Microdrives, is due to a manufacturing change that was implemented recently in IBM's line of miniature hard drives. The revised controller chip, though it should not affect overall performance of the Microdrive, did introduce a slight difference in the timing of response to certain camera commands, hence the resulting D1X problem.
Though it's acknowledged that the error is IBM's in this case, Nikon is promising to develop a solution for the camera, most likely in the form of a firmware update for the few D1X's that have already shipped. Full details of Nikon's solution are to be revealed by the end of June. Nikon has posted a statement about this on their Japanese-language web site (English translation).
To determine if your 512MB or 1GB Microdrive contains the controller chip change, look at the serial number on the back, beneath the bar code. If the first character of the last three in the serial number is something other than "0' then the card will not work in a D1X that has already shipped, at least not until Nikon offers a fix. My Microdrive below has a serial number whose last three characters are "08A". The first character is a "0", which means this Microdrive will operate normally (which it does!), as it is a version of the card similar to that which Nikon used in its certification testing.
The last three characters in the serial number are the key to determining
whether a 512MB or 1GB Microdrive is affected. If the first character in the
grouping of three (here, "08A") is something other than "0" (zero), then the
card will not function in the D1X cameras that have shipped to date, at least
not until Nikon's fix for the problem is available.
Remember, however, that this incompatibility problem should be short-lived, given Nikon's intent to solve it quickly. Other cards certified by Nikon for use in the D1X, including various brands of CompactFlash flash memory cards, are not affected by this incompatibility and should operate as expected in the camera.