Today I clicked on Apps again and noticed an error/warning that curl wasn't installed. Installed it directly with apt-get install php5-curl and then the apps popped up. Now, a few hours later no apps are visible and even if I press update nothing appears. I found an error from a few days ago (over a week) that the directory plugins-core wasn't present. I made this and changed ownership to ispconfig:ispconfig but w/o any result so far. Did try to debug ispconfig with the faqforge debug tutorial.. no errors appeared. I'm using the standard repository btw, Ubuntu 12.04 LTS, multiserver setup (web & db; mail & dns).