|Do you have an add in sound card or are you using the integrated sound? |
Either way, the sound is most likely running on the PCI bus. The PCI bus is a shared bus. On enthusiast motherboards there are some adjustments to the way the bus is shared. On a Dell I doubt any settings are available.
Go into Device Manager and highlight the top line. Select View> resources by type> expand Interrupt Request. Look for the listing for the sound and see what IRQ is assigned to it. Then look for all other hardware that is also using (sharing) that IRQ.
List all hardware sharing the IRQ and also the IRQ number.