After upgrading to GNOME 2.26 and the very latest Tasque, I no longer show any “Task Management System” in the preferences.

** (Tasque:17844): WARNING **: The following assembly referenced from /usr/lib64/tasque/Tasque.exe could not be loaded: Assembly: RtmNet (assemblyref_index=13)

It turned out that the DLL it needed, RtmNet.dll, was in /usr/lib/tasque instead of /usr/lib64/tasque where Tasque was looking for it.

To fix:

sudo su -
cd /usr/lib64/tasque
ln -s /usr/lib/tasque/RtmNet.dll .

I assume the dll is 32-bit instead of 64-bit and I have no idea if it’s intentional or what.