Please read this whole message carefully, especially the warnings, before doing anything.
WARNING: The changes to your configuration suggested here should be regarded as provisional; they may not solve your problem, or they may remove functionality that you consider to be useful. If a third-party system modification that you want to keep is causing the problem, you’ll have to seek help from its developer.
WARNING: Back up all data if you haven’t already done so. Before proceeding, you must be sure you can restore your system to the state it’s in now, even if it becomes unbootable -- which might happen. If you’re dissatisfied with the results of the procedure suggested below, restore from your backup.
You should either update or uninstall the following system modification(s), if an update is available from the developer:
Flash Player
Default Folder
1Password
and definitely remove at least the following:
Ambrosia audio driver
CleanApp
RealPlayer
Silverlight
EvernoteSafariClipperPlugin and Macromedia (in [home folder]/Library/Internet Plug-Ins)
Smile (Satimage)
† DivX
† AdobePDFViewer (in /Library/Internet Plug-Ins)
All of the latter must be removed completely, and (unless otherwise specified above) the only way to do that is to use the uninstallation tool provided, if any, or to follow the developer's instructions. In some cases it may be necessary to re-download or even reinstall the software in order to get rid of it. I can't be more specific, because I don't install such things myself.
WARNING: Trying to remove complex system modifications by hunting for files by name usually will not work and may make matters worse.
I recommend that you never reinstall the modifications marked with a dagger (†) above, if any. If your problem is resolved after uninstalling all the above modifications and rebooting, but you still want to use some of those not marked with a dagger, you can experiment with putting them back, one at a time, testing carefully after each step. Keep in mind that system modifications may be incompatible with each other or with future Mac OS updates, so it may not be clear which one is at fault.
Never install any third-party software unless you're sure you know how to uninstall it; otherwise you may create problems that are very hard to solve.
If you still have problems after making the suggested changes and rebooting, post again. Remember: if you don’t like the results of this procedure, you can undo it by restoring from the last backup you made before you started.