As for the possibility that too much IR is getting to the DVD and VCR, I have run into this...I once had to teach Sony DSS commands to a Lexicon remote from three feet away, because otherwise the Lexicon signal was too strong and I had to point the remote somewhat away from the DSS to have it work properly!

Try lowering the current that goes into the VCR and DVD LEDs by adding a resistor in series with each of them. If they are not dual LEDs, do this process with each one of them. I know this means cutting open the wire, but it might give you a perfect solution.

Get a 2000 or so ohm pot and wire it in series with the LED, wiring to the center terminal and one other terminal of the pot, and experiment with different settings of this pot to see if you get total success at some position. Then remove the pot from the circuit, carefully measure the resistance between the terminals the LED was connected to, and put in that place a 1/4 or 1/8 watt resistor as close to this value as you can.