MpG, it appears we have very similiar problems here. My sound card is also Sound Blaster Audigy and I connect to the Internet using modem. And my PC will too, hang (blue screen) whenever I play song and go online at the same time, like you too even a simple sound will crash my system. My Windows version is also XP Professional SP2.

Anyway, after doing many checks I highly doubt the problem has something to do with the lack of power supply, I'm more believe that it has something to do with the modem and sound card using 'sound channel' or whatever request at the same time and the system can't handle it, therefore causing crash. Installing latest driver didn't help, in fact I strongly advise you not to install latest Audigy driver from Creative website because it has caused my sound to become somewhat bleary (DxDiag even now only recognize my sound card as 'emulated'). Just stick with the driver in the CD supplied by Creative that came with your sound card package box.

By the way, it has been more than one month since you posted this thread, have you find any solution to this? I haven't found any solution that worked, and have to switch back to onboard audio whenever I go to internet.

Well , I found a solution two days ago- if you can call it that way- I used an older modem(!!) from a 5 year old PC and it just worked.Yeah it must must be lack of power supply but I don't now whose fault it is...A friend of my has the same problem so it must be the audigy. Good Luck!!!

Lol...really? So you can now turn on the internet (online) and music (sound) at the same time using your sound card? Well, 2 weeks ago I was trying to work the way around it but it ended up corrupting my PC OS and I had to reformat the HD! Although my PC started to slowly going back normal after that, my sound card and modem still refuse to work together. My 'very temporary' solution to solve it is that whenever I want to use internet I'm making sure I use the on-board audio instead of sound card (change sound settings from Control Panel)...

it may have something to do with the fact most modems have that annoying modem noise thats a sound device and i think maybe the music gets confused as to which to use