Strange lockup

A week or so ago I ask about this on the Fedora list, but no one there seems to have seen what I am seeing. I have no idea where else to ask. --------------- Sometime after the first or second update to Fedora 17 I started noticing that Firefox, Thunderbird, Chrome and Gkrellm would stop updating their screens and be unresponsive. It starts off slowly, in that first I notice one of the above apps doesn't paint immediately after switching to the desktop where that app is running. Then as time goes by it takes longer and longer for those app's to paint. Note that even after they get painted they aren't immediately interactive either. If I switch to a virtual terminal and run top, I see that each of these apps are at 100%, plus I notice that if I look at the virtual terminal as soon as I switch desktops to a non responsive app I see the abrt-applet is also at 100%. Except for abrt-applet, once I see one of these apps hit 100%, they never decrease until I kill them. If I kill one of the apps and restart it, that app works again for a while. My system is running KDE and is fully updated via the default repositories. Since I first asked about this on the Fedora list, I uninstalled the abrt-applet RPM, so I don't see it in top anymore, but the other apps are still doing the same thing. One thing I noticed is that if I am not switching between desktops a lot this problem doesn't seem to happen. For example, if I leave my workstation of a couple of hours, when I get back all is well. Is anybody else seeing this? Any ideas? Emmett