Since V Pro 10 never claimed compatibility with Windows 8, I'm not certain if this will help - but, if you did an "upgrade" to 8 instead of a clean install, it's possible that the latency of your audio hardware interfacing with the O/S might have changed and Vegas is still using the old settings. Check in the Preferences tab under "audio device" and if the checkbox to automatically adjust for latency isn't checked, check it and see if that helps. If not, or if the checkbox was already selected, then uncheck it and see if you can manually adjust the latency to be useable.