This may help:
This solution worked for me:
"Fixing sound performance on an Acer laptop
Posted by Chris Corrigan - 23/01/07 at 12:01:29 am
I bought a new laptop last Friday - and Acer Aspire 5570 - and Iím finally happy with it, but it took a few days. THere was an annoying problem with poor sound and DVD performance, that seemed as if there was a big elephant hoggin memory somewhere. I tried dozens of solutions and finally found this guy, who tried everything I did too, except he solved the problem:
What I did to fix it was to go to the HARDWARE part under the SYSTEM options (Control Painel). Under the IDE Controllers part I had PRIMARY IDE and the INTEL one. What I did was right click and select UNINSTALL on the IDE oneÖ When I rebooted the whole machine was way faster, specially sound playback. Under the IDE Controllers I still get the same icons (Primary IDE and the Intel one) but Iím 100% sure that this was the cause of the fix.
It worked for me as well, and everything just hums now."
Note: Don't need to read this part:
After about 7 months of having an Acer Aspire One laptop, my computer suddenly had the sound problems and became super slow. I eventually realized that it must be a RAM problem/problem with processes, so I found RAM Idle LE, which is nice but doesn't do much. Though with this I noticed that when I had sound problems while watching something, the RAM dropped to 0 and then back up when the sound went back to normal. I also did lots of computer cleaning, CCleaner, defragmenting, compressing, and disabling some of the processes that start automatically when the computer starts (which I'd recommend doing). And then I looked up a solution to this specific problem and found one. My laptop is back to being amazing.