My 3910 stops playing cd´s (fex,in the middle of a cd)and a clicking sound is heard,and I have to shut down the player to start again,I have changed the laser and the laser board(the one with the motors on)Is therer anything else I have to do to make it work?

Edit:sommetimes I can paly a whole cd ,sommetimes just a few songs.Works better when its cold.Do I have reset the laser in some way?

Where do I get Firmware,and how do I install it?
FoundFirmware and uppgraded,still stops palying cds

It sounds like your laser assembly is starting to fail...I have had my DVD-3910 for almost 5 years and it's starting to act sluggish on Redbook CDs but still plays all other material flawlessly. Here is a link to the "DVD-3910 Owners thread and if you use the "Search this Thread" (Upper right corner) with "laser," you should get some folks experience with this problem: http://www.avsforum.com/avs-vb/showthread.php?t=447795&highlight=3910+owners

EDIT: If the link above doesn't direct you to the Denon DVD-3910 Owners Thread use the search function on the DVD-Forum with words "3910 owners."