Start by looking at this other thread on a similar issue and try all the troubleshooting things mentioned there.
http://duc.avid.com/showthread.php?p=1955128
There was really no need to install PT 9 first and I would always fully remove an old version before doing a new full install when upgrading. You may want to uninstall everything and try a new PT 10 install and see if the standard plugins work before installing any additional ones. I would try trashing press/database etc and a new user account and if none of those work then a full uninstall followed by a full PT 10 install.
Darryl