Hi,
Things to try to resolve the problem:
a). [https://forums.lenovo.com/t5/Lenovo-Android-based-Tablets-and/Lenovo-TAB-2-70F/m-p/3727390|Wipe the cache partition] and check if this resolves the problem
b). Try starting the tablet in [https://support.lenovo.com/au/en/solutions/ht104358-simulator-how-to-enter-and-exit-safe-mode-a10-70-tablet-a7600|safe mode] and check if the problem still occurs or not.
Being random makes it difficult so you may have to use it in this mode for a while to make sure that it doesn't occur.
If it doesn’t happen at all when in safe mode, then a ''downloaded'' app is the cause of the problem. The trick is to find out which one is the culprit. You will need to uninstall each ''downloaded'' app, one by one and operate the tablet in ''normal'' mode between each uninstall. When the tablet works OK in normal mode then the last downloaded app that was uninstalled was the cause of the problem