After I installed SIG I noticed that the Admin Menu was broken (no more dropdown).
Looking on the Joomla forum pointed me to issues with mootools.
I did check the content of the /media folder and I noticed it had been wiped clean!
only jw_sig remains.
I tried to copy the /media/system folder from a brand new joomla install but it did not make a difference.
Joomla now finds mootols.js when the admin page loads but it is still throwing the following error:
Uncaught ReferenceError: Accordion is not defined.

Please help me fixing the mess that installing SIG created.
thanks!

Hello,

Sig will not delete any files.
Make sure the that jQuery is not being loaded twice in your site.