P5B Deluxe (Another) Audio Problem!

OK this is really frustrating and I have been trying to work it our for quite some time now but nothing works. I need any help you guys can provide.

Configuration:
Asus P5B Deluxe
Intel Core 2 Duo 2.13 MHz
Kingston HyperX 8500, 2 x 1 GB DDR2 Dimms
Asus VGA EN7600GT Silent 256 MB
Creative SB Audigy Platinum 5.1 (Yes the old one)
Enermax 500 Watt Power Supply
3 SATA HDDs & 2 Sony Optical Drives on IDE Controller

The problem is that I get no sound from the center channel when using 5.1 configuration for my Logitech Z5450 Wireless speakers. This is what I've tried so far:

1. Formatted my system and reinstalled the devices one by one. The center channel may work from time to time but with no apparent reason it stops after some time.

2. I disabled my Audigy and tried the onboard audio system. Same problem. I reformatted my PC with no Audigy plugged in, just onboard sound enabled. Same issue again.

3. I connected my old Altec Lansing 5100 speakers. Same problem.

4. I changed cables between the PC and the speakers. Same problem.

5. I tried different codecs and players, each time formatting my drive just to make sure that no garbage is left inside. Nothing worked.

6. Upgrading to the latest BIOS did nothing for me.

7. I completed a new format not connecting any unnecessary internal or external devices. Just board device drivers, creative drivers and VGA. Same damn thing even when I did the same thing with the onboard audio and no creative installed.

8. I even tried Vista with beta creative drivers. Same problem.

To sum up:

1. It is NOT a faulty Audigy card because the same thing happens with the onboard audio.

2. It is NOT faulty speakers because I tried my older set with no luck.

3. It is NOT the cabling cause I tried a new set.

4. It is NOT my windows set up cause I formatted my drive countless times using original Windows. Even tried Vista RC1.

5. It doesn't seem to be the board because there are times after a format that the system works flawlessly.

There was one time that I managed to get everything working and thought I had found the reason behind this hell although it did not make much sense. I noticed that when I connected my Logitech USB Web Camera the problem occurred. When I disconnected it was fine. So I left it disconnected. After two days the problem re-emerged with no reason what so ever.

Any ideas? Any...