Existing lock /var/run/yum.pid: another copy is running

This is a very common error which you might come across in Red Hat Linux distro while trying to run yum command Error: # yum install bind Loaded plugins: fastestmirror, refresh-packagekit, security Existing lock /var/run/yum.pid:

Fix "usr/bin/Xvnc: undefined symbol: pixman_composite_trapezoids"

This is one another error which appears while trying to restart vncserver services which came to me in CentOS 6.2. Error: /usr/bin/Xvnc: symbol lookup error: /usr/bin/Xvnc: undefined symbol: pixman_composite_trapezoids /usr/bin/Xvnc: symbol lookup error: /usr/bin/Xvnc: undefined symbol: