I have been suffering from the same issue - or so it seems. Basically, I can record with no problems. However, during playback, I'll get this popping, then stuttering note sound effect. It almost sounds like it's set into a continual echo effect.
It appears that this is a somewhat common problem across all kinds of interfaces, and systems. For me, I have a Presonus FP10 interface with Cubase 4 LE, and am currently running off a laptop, with some cheap laptop speakers (ughh...I know
). It doesn't seem to be the CPU usage because it never gets all that high.
What is weird is this problem started on it's own at some point, with nothing to indicate a source (like loading a new antivirus program etc), because before a couple of months ago, there were NO issues with my Cubase LE.
I did try changing the latency to a higher millisecond setting last night (from 4 ms to 12 ms), and that does seem to work, but I did still get pops/stuttering after doing that. Maybe I'll just keep increasing it. Is there a limit to how high you should go on latency?