[themes] theme keeps disabling

I've got a weird problem my theme. I've got 2 custom theme, one default for main website and another admin theme. I also use sections module to simulate a joomla-like admin page. problem here is that admin theme becomes disabled sometimes so admin users see admin page with default theme! so everytime I have to login user/1 and enable admin theme.

I have no idea why this happen but kinda feel like mostly when I visit a alias, run cron(not all the crons) or add new section.

this one happens everyday or 2. any1 can help me out here? I'm done with the site which I'm working for a month on it, but can't install it for my client yet since this crit bug