The best remote Powerpoint Presenter?

OK I'm at wits end. I have tried 4 different types of Powerpoint Remote Presenters. These are the little gizmo's that speakers use to advance slides in their Powerpoint Presentations. Logitech and Gyration, are the latest two I have worked with and which are supposed to be 100 foot range, 900 Mhz and 2.4 Ghz models. They seem to work until the room starts to fill up with people and then they just peter out and will not consistently advance or return to the previous slide much less do any of the special things they claim to be able to do. What do you guys use?

Here are the salient facts of the area in which this Presenter needs to operate. The room is 75 feet long by 40 feet wide and will usually have at least 25–300+ people present. The speaker is usually about 50-60 feet from the receiver, there are no columns or walls the stage is elevated and the AV booth is elevated so that even if people are standing the transmitter/receiver has clear line of sight. With less than 50 people in the room the Presenter seems to work fine with over fifty people the successful operation of the Presenter is doubtful. I don’t know what it is about people but either they absorb the radio signal or all the cell phones and other electronic gizmo’s they carry around with them seem to interfere with the signal. The room is wired for sound but most of the wires run under the stage. The AV booth has some sound, video and computer equipment but other than that and the lights there are no other signals or wires in the area I know of that interfere with the signal. Your help and advice is much appreciated.

Wildkow

p.s. I have found one that seems to work but that model is no longer being made and it has no other features than Next/Previous slide and blank screen. It would be nice to have laser and a means to point at the slide with a onscreen cursor or to highlight things on the fly.