HAve you thoughourly tested the power supply in the system. It sounds to me like you've finnaly crossed the line on the maximum wattage of the PSU (power supply unit).
This also explains the CD ROM issues. If the CD ROM is trying to initialise, and there is not enough power the system will sit there waiting for the CD.
In my experience the beeping your hearing is always the result of a power shortage on the motherboard. This has happened to me resently when the power cable to my PSU was not making a 100% connection..In my case it was just a matter of making sure the cable was firmly in the back of the tower, but to me this sounds like with all the CD, HDD and devices in the machine, you're simmply using more power then the PSU has to give.
My guess is that the video card is using some form of APM and its not until you go to access some of the specific hardware on the card that its sucks more power then you have. Or possibly its not the Video card at all, but when veiw media files, the SOUND CARD (SB Live!) is sucking more then ussual (to intiate all those cool SB Live! features).
I'd get a bigger PSU and give it a go...but if its a HP, or comapaq or other prebuilt machine, make sure you check that the stuff they use can handle it...My mate had a HP pavilion 8600 (with a pathetic 185W PSU and he discovered that if he DID upgrade the PSU, there was a VERY high chance he would kill his mobo - who knows how THAT works??)
I hope this helps...let us know?
