I had pidgin running fine and showing up in systray with Fedora 11. After update to F12 I still see a systray with e.g. nm-applet, but after starting pidgin its icon does NOT appear in the systray. However pidgin is started (says ps). Maybe other programs are affected as well? Don't know yet ...
Hmmm, somebody on #fedora-kde reported something similar with the KDE keyboard layout indicator/switcher. In his case, putting a different graphics card into the machine "fixed" it (a quite drastic "solution"), so it seems to be some video driver issue (yet another one :-( ). What video driver are you using?
The nvidia-proprietary as shipped by rpmforge. (Please no flamewar about proprietary drivers - I need acceleration, so nouveau doesn't yet help out for this graphics-card). I reported a graphics-error with the latest xorg in bug #538344 - I thought that was unrelated, but now that you write it might be graphics-card-related ... hmm ...
You shouldn't be getting flamed for using it, but our usual process is that you also see if it happens with nouveau. If it does, we can do something about it on our side. If not, there's nothing we can do to help, and reporting it to nvidia is the next step. As for the bug, it's a duplicate of another, I'll look for that bug.
As my problem surrounded pidgin I took some more time to further diagnose the issue. Starting pidgin in strace I saw that right before pidgin "hung" it loaded /usr/lib64/gstreamer-0.10/libgstladspa.so (from gstreamer-plugins-good) and a few lines after stopped starting inside a FUTEX_WAIT_PRIVATE. Removing gstreamer-plugins-good from the system (without taking into account any deps) pidgin started fine on the next run, initialised and also showed up in the systray correctly. So it seems it only didn't make it through (pre-)initialisation-phase. Strange thing is that now after re-installing the very same version of gstreamer-plugins-good again through yum it now still works. gstreamer-plugins-good-0.10.16-7.fc12.x86_64 pidgin-2.6.3-2.fc12.x86_64 Could somebody maybe move this bug to gstreamer and re-label the bug-title or so? But I'm not sure how to reproduce/track down this issue - sorry.
Reassigning, though as it fixed itself after a reinstall, reproducing the issue may be hard to do.
I'd need a backtrace of Pidgin hanging.
I'm not sure it's reproducible anymore. At least the problem I experienced went away after reinstalling the gstreamer-plugind-good-package and until now didn't reoccur.
Cool, closing then.