[R-sig-Fedora] x11() hangs in R 3.2.1

[Ashley Ford]

Yes, I have nvidia,
recent updates includexorg-x11-drv-nvidia-devel-352.39-1.el6.x86_64 Tue 08 Sep 2015 04:07:42 PM BSTxorg-x11-drv-nvidia-gl-352.39-1.el6.x86_64    Tue 08 Sep 2015 04:04:03 PM BSTxorg-x11-drv-nvidia-libs-352.39-1.el6.x86_64  Tue 08 Sep 2015 04:04:01 PM BSTxorg-x11-drv-nvidia-352.39-1.el6.x86_64       Tue 08 Sep 2015 04:04:00 PM BST
 So far I have failed to find a copy of the old centos rpm 
  
 http://rpm.pbone.net/ points at a location that doesn't exist, So  I tried using the redhat rpm  xorg-x11-server-Xorg-1.15.0-26.el6_6.x86_64.rpm but the downgrade fails, is yum out of step with rpm ?
as given
# yum downgrade xorg-x11-server-Xorg-1.15.0-36.el6.x86_64 ./xorg-x11-server-Xorg-1.15.0-26.el6_6.x86_64.rpm
Loaded plugins: auto-update-debuginfo, fastestmirror, refresh-packagekit, security
Setting up Downgrade Process
Loading mirror speeds from cached hostfile
 * base: mirror.ox.ac.uk
 * epel: mirror.nl.leaseweb.net
 * epel-debuginfo: mirror.nl.leaseweb.net
 * extras: centos.serverspace.co.uk
 * updates: centos.serverspace.co.uk
No package xorg-x11-server-Xorg-1.15.0-36.el6.x86_64 available.
Examining ./xorg-x11-server-Xorg-1.15.0-26.el6_6.x86_64.rpm: xorg-x11-server-Xorg-1.15.0-26.el6_6.x86_64
Nothing to do
and omitting the last part of the rpm name 
# yum downgrade xorg-x11-server-Xorg-1.15.0 ./xorg-x11-server-Xorg-1.15.0-26.el6_6.x86_64.rpmLoaded plugins: auto-update-debuginfo, fastestmirror, refresh-packagekit, security
Setting up Downgrade Process
...
Examining ./xorg-x11-server-Xorg-1.15.0-26.el6_6.x86_64.rpm: xorg-x11-server-Xorg-1.15.0-26.el6_6.x86_64
Nothing to do
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