i also have this issue with a new mac mini 2012 model. this model also has an intel hd 4000 built in.
i have a dual monitor setup. both monitors have a dvi in. the mac has one thunderbolt out and one hdmi out. the random "blackouts" - monitor just goes into standby and back on for a second - (happened twice yesterday) occur on the hdmi connected monitor. at first i thought it is an issue with the hdmi out - but after just using only one monitor on that connection for several hours the problem did not happen again.
so it also may be a driver issue in this case.
there is not much to find about this issue on the internet yet - first the mac mini 2012 model is still very young and also i think not many people have a dual monitor setup with a mac mini.
i wonder if other intel hd 4000 users, or maybe even mac mini 2012 users, have the same issue...
