I have two Dreamboxes.
I've been playing PES4 Beta extensively with my mate and have experienced NO PROBLEMS.
I test it with LIVE and all was ok, but because of the questions in this thread, I did some extensive testing on:
Mech...whatever it is.
Moto GP and
Splinter Cell.
I can report, again, NO PROBLEMS, the headset worked perfectly, though as mentioned, it does seem a little loose sometimes (on the Dreambox socket).
I even retested with/without the GAME extension cable - both gave same results.
People having problems, can I suggest something. When I first put player two's dreambox and dual shock in on PES, the controller would not move on the controller selector screen, i.e. it was not being recognised. On checking the PS2 pad it was slightly out of the dreambox - once fixed in properly, it was perfect. Some of your problems could be because of a loose connection? Maybe? Jjust trying to help.