Whenever i have had similar problems to this on other devices, it's usually an IR sensitivity issue. That is to say that you may be getting a constant low level flood of IR into the device via emitters that saturates a sensitive IR reciever on the device that an extended push manages to get through but a quick pulse does not.

Another posibility may be that IR from other emitters is bouncing around inside the cupboard and interfering with the IR going directly to your DVD player(including IR from the back of it's own emitter bouncing off the cupboard door). If the DVD player is more sensitive to IR than the other devices it can affect only that device.

I would firstly shield the IR window on the DVD player completely so that no other IR can possibly get into it and if that doesn't work try reducing the amount of IR going into the device from it's own emitter as well as shielding it from other possible IR sources.
A layer of white electrical tape between the emitter and the IR window usually works well although i have had occasions where i have had to use up to 4 layers to get enough reduction for reliable use.

I have made the assumption that you are using IR repeating equipment and that your equipment is in a closed cupboard here.
If it isn't, lets have some more details of how the equipment is housed and what other equipment is involved in the control side of things. Also what kind of display device are you using?

I hope some of this helps.

Simon.