If I may pop in on this, have you tried using the OnBoard Sound Adapter (the built-in audio device on the motherboard/mainboard)? I only ask because you state you are using a USB Audio Adapter. There is nothing wrong with these (I myself am using a USB adapter that came with my headset), I am just wondering if it is having an issue potentially contributing to this synchronization problem. Have you tried a Sound Card (a discrete/separate board with its' own audio processing)? Even a cheap one may also alleviate a problem like this. Were you having trouble before you tried the USB Audio Device?
Just some Suggestions/Questions off the top of my head, in an effort to help out...