My problem is this:
whenever i reboot my device, and start an app, i lose my close/cross buttons at the top along with the app titlebar.
When i open an app, initially, the titlebar and cross buttons are shown along with the busy rotating indicator. When I switch to taskbar and back, I lose the titlebar and close buttons.

This is solved temporarily by changing the theme but on the next reboot, the problem reappears.

the only thing i had installed recently before this problem was nitdroid 11, but now i have removed it.

could somebody please help me?

Also, could be related, I am getting "no sim" indications now.