Most likely DPI is set incorrectly. The method the driver uses to compuete DPI changed (and may be buggy). See the thread on DPI, http://www.nvnews.net/vbulletin/showthread.php?t=61189
, and 1.8174. Try setting Option "UseEdidDPI"="false". This should allow the DPI to compute properly. Good Luck! Report back.