DVD Player / Cooling Fans

Installed DEI dvd player DV2600 (nice unit).  Played it that night continuous - driving, parked, and driving again for about an hour straight.  The unit locked up and froze while driving.  No response from power button or remote control input.  Hit the reset button and regained control.  Unit was pretty warm - I believe it locked up from excessive heat.   DVD spins faster than CD and I would guess generates more heat? 

Din-size DEI player installed indash underneath the monitor-only Sony XAV7W.  The monitor slides out from the bottom (not the top of the head unit) so heat from the Sony should not be a contributing factor.  If anything, the head unit on top should be affected by the heat coming from the dvd player - not vice versa. 

1.  Is overheating a "normal" side effect for mobile dvd players?

2.  What are the quietest, smallest cooling fans for an application like this?

Thanks in advance for your input.

I had a nice off-brand din-size player with a fan built-in and that one slowly but surely crapped.  Unit would freeze, not play again, and finally got to a point where it will accept a disc, but wont recognize it after several attempt to scan...."no disc" it would read.  The luck huh?  Dont stand next to ME if you hear thunder...