Google Earth reports "drmWaitVBlank returned -1"

[Jonathan Ryshpan]

I've just loaded the latest version of Google Earth.  About 3 seconds
after I start it from a console the following message appears on the
console:
        do_wait: drmWaitVBlank returned -1, IRQs don't seem to be working correctly.
        Try running with LIBGL_THROTTLE_REFRESH and LIBL_SYNC_REFRESH unset.
After about a minute Google Earth starts and appears to run OK.

Does anyone know what this message means?  How can it be avoided?  

Could it be related to X-Windows driver problems?  Every few days my
monitor puts our a message that it's out of sync and goes dark; the
message (and going dark) are exactly what appear when the computer is
turned off.  I can get the screen back by going to a non-X console (ie.
by pressing CTL-ALT-F1) and then going back to X-Windows (ie. by
pressing ALT-F7).

Thanks - jon