Most likely your problem relates to the addition of your external hard drive. Like it was said earlier, your system may be hogged by other programs that are higher on the IRQ. An IRQ is a line in which your microprocessor works. Since your computer has only one microchip and cannot complete more than one task at once. It will run through a list of programs in which a single job must be completed. Your sound (or hard drive) might be low on the IRQ which will allow a longer gap between when the microprocessor can complete its job ( start sound) on it. Your IRQ on a "plug and play " hard ware or software piece should already be designated when the driver is loaded. Changing your IRQ through a DIP switch is is tricky and can have bad results. Also if you have sound capabilities on your motherboard you should turn them off through BIOS this will also free up space for the IRQ.