Hi Jim,
It seems that the js conflict between our Mega menu and Simple Gallery Pro plugin that causes the menu dropdown not work properly. In this case, you can try to do:
– Temporarily disable this Simple Gallery Pro plugin and check out the Mega menu again.
– Update the K2 v2.6.7 and configure it to load jQuery 1.8 or higher of Google Ajax (It is loading the jQuery 1.6 yet).
Do not forget to clear JAT3 cache after updating changes.
For the issues of Content Slider and Slideshow module, you can send me PM with valid admin login info. I will help you to check and try to correct those issues.