Are you seeing any "flickering" lights at the same time. If you go into BIOS (F2 on boot) and just leave the machine in that state for a few minutes, does the sound continue. If you unplug the A/C adapter form the A/C source and run the unit on batteries soes the sound continue.
Something like that would help isolate the cause and then maybe we can go from there.
This is buzzing from the actual laptop, and the processor active light flashes during the buzzing and mouse freezing. I'll try it with BIOS and battery tho, it's possible my power brick is defective since it makes faint clicking noise when I put my ear to it.
Are you running anti-virus software and spyware type of things. See what is running (look in task manager) as you might have something running in the background that could be causing it. What are the internal temperatures (Mobil Meter is a good tool) - it could be the varying fan speed oscillation that you are describing as a "buzzing sound" where the fans are working to cool the system because of a background task consuming a lot of CPU resources and "heating up" the machine.
DLLRUN.exe and INCD are two programs that are know to cause errant CPU loading.
No CD's in drive. Antivirus is all there is but that's always been there and I disable it. I've tried closing processes with no success. The two you mentioned are not running. I'll download the Mobil Meter as soon as I get internet connection going (the laptop has poor internet hardware so it's difficult - wired doesn't detect any connections, wireless often doesn't work)