Due to a problem in the Quartus® II software versions 10.0 through 10.1 SP1, the ALTLVDS_TX MegaWizard™ Plug-In Manager may fail to open if you do not have all device libraries installed. Note that this affects only the ALTLVDS_TX megafunction, not the ALTLVDS_RX megafunction.
To work around this problem, reinstall the Quartus II software including all device libraries. The ALTLVDS_TX MegaWizard Plug-In Manager then functions correctly.
This problem is fixed beginning with the Quartus II software version 11.0.