What I have tried so far without success
- Removed "Quartz Composer Visualizer.bundle" from Itunes plugins directory (no change)
- Set Itunes to start in 32 bit mode (no change)
- Updated to latest 10.5.1 (no change)
- Disabled all network access for Itunes (no change)
I checked again and it appears to be happening every 2.5 - 3 seconds and not 5 seconds as I originally posted.
Every single other app is running smooth as ever, just itunes that is giving me grief.
For those interested or also experiencing this I finally found the problem.
The problem is related to the kext "AppleUpstreamUserClient.kxt" I only found this out after a LOT of Googling.
The trick is to rename the kext and repair permissions and voila, no more skipping mouse.
sudo mv AppleUpstreamUserClient.kext AppleUpstreamUserClient.kext.old
When you do future OS updates it could restore the kext so you may have to disable it again if you start having the skipping mouse problem again. I hope it works for you if you are experiencing this problem.
Well I guess I spoke too soon. After a couple of hours of listening to music in iTunes with no problems, the mouse "skipping" problem is back.
It actually seems related to my second display (On a mini-displayport to DVI adapter output) and iTunes than anything. Unplugging the display port adapter stops the iTunes skipping. So I guess I have to choose between iTunes and my second monitor.
No, it's fine with one DVI connected display. Disconnecting either the DisplayPort to DVI adapter from the computer or unplugging the second monitor (Samsung) from the electrical outlet eliminates the problem. As long as the second monitor is powered on everything is ok, it's turning off the second monitor that causes the mouse skipping.
There is more on it here if you're interested...
(This one is not a "new" problem or necessarily related to Lion, as you can see since the first post was from 2009, which coincidentally was the year DisplayPort appeard on Macs if I'm not mistaken).
The problem exists even if iTunes is not open, I recently realized as my mouse has become way more accurate on the desktop! Having iTunes open does make the mouse skipping 10X worse though!