WYSIWIG is just a java application I believe (I don't think it is pure javascript but I've never looked closely) so no surprise that it would also break for you.
If you haven't yet definitely follow GDs suggestion in looking for malware on the computer.
Do you get any kind of error message when the java applications fail to run or is it just that nothing happens?
Otherwise, off the top of my head one thing you may want to check is in the Java Control Panel.
Open that up (if you have the little coffee cup icon in your system tray double click it or you can run the file at C:\Program Files\Java\jre.1.50\bin\javacpl.exe in a default Java install)
In the control panel, go to the Advanced tab.
On the Advanced tab expand the <APPLET> tag support line and confirm that the box for Internet Explorer is checked. If not, check it. If it is, then that isn't the source of the problem.