It's a problem with your monitor not being able to supply the frequency
your video card is asking for (at least not at the resolution it's set to).
H. is horizontal
V. is vertical
Possible fixes vary from changing frequency, as described here
https://answers.yahoo.com/question/index?qid=20090602200306AAh5qiTto installing an older version of video drivers, as described in Post #16 here
http://forums.hexus.net/graphics-cards/11745-what-hell-hv-frequency-over-range.htmlAnd since you're only seeing the problem with games, you might try going into the "Games Video Interface" as described here
http://www.techrepublic.com/forums/questions/hv-frequency-over-range/(I don't remember seeing a frequency option in a Game interface, but maybe it's there in some games. However many games allow you to change in-game resolution, so you can try that.)
It may help to install drivers for your monitor, if there are any.
It may be your monitor can support higher resolutions and frequencies
than the "auto-detect" Plug 'n Play drivers indicate.