I upgraded my NextGen gallery to version 2 only to find out what a mess it is. It completely ruined my WP install. When I tried to follow their how-to to roll back to previous version, it worked — I was able to restore 1.9.13 version without losing any data, it seems so far. But, there was one big issue left — the visual editor stopped working. It was completely blank with no icons and no ability to enter text. The HTML editor worked fine though.
Having disabled all the plugins I was able to detect that the one causing the problem was the NGG. With NGG disabled, the visual editor worked. The moment I activated the NGG plugin, the visual editor was left blank. I tried to google the solution, but none of the advice I found worked for me. The so-called “support forum” on NGG’s WordPress site had no answers for this issue.
Today it stroke me — I had a proper look at the NGG’s file and folder permissions in my WP install directory — guess what… all the directories were set to 750 and all the files to 640. I chmoded them to 755 and 644 respectively, and voila… everything works now.