Previously mentioned fixes include removing login and startup items, or deleting errant kernel extensions, clearing kernel extensions, and more. Unfortunately, some users have only been able to find respite by downgrading to Mac OS X 10.6.2.
Users continue to experience intermittent mouse/keyboard freezes and/or system stalls after the update to Mac OS X 10.6.3. The issue is typified by the cursor freezing in place, or text input becoming suddenly interrupted then catching up a few seconds later, and is covered in our Mac OS X 10.6.3 troubleshooting guide.
New fix: turn off Spotlight
While we previously mentioned that re-indexing Spotlight may partially resolve this issue, it now appears that turning Spotlight off completely eliminates the problem entirely for some users.
To do this, simply open System Preferences and select Spotlight. Navigate to the “Privacy” tab and drag your startup drive’s icon to the pane. Repeat this for any other volumes (disks) you’d like to exclude.
You can also turn off Spotlight using Spotless, a tool that allows you to delete existing Spotlight indexes as well.