Thanks to the mandatory Ethernet port on every HD DVD player, the first generation products (Toshiba player models HD-XA1, HD-A1 and HD-D1) can now be updated to firmware version 2.1. According to the release notes, the firmware update adds support for "certain anticipated network delivered content" in future HD DVD discs. Also addressed are issues where HDMI output does not work or works intermittently with HDTVs or monitors and improvements in playback to eliminate pixelization, block noise and audio dropouts. Several HD DVD players appear to be due for firmware updates given the recent breakout of compatibility problems. For example, Children of Men is giving HD DVD owners a headache, with reports of freezing or refusal to play, even after trying multiple, retail exchanged copies of the movie.