I am using Ubuntu 18.04.4 LTS on Toshiba Satellite Pro laptop with Intel Centrino 2 (yes, it's a very old one, around 9 years, but it's working so why get rid of it) and everything was fine until the last Linux kernel update (4.15.0-91-generic).
After this update whenever I wake up the laptop by opening the lid from suspend state, it suspends itself again after some 30 seconds or so. The only thing I can do with it is to quickly restart. After restart it works well again, until the next suspend and then the whole things repeats itself.
EDIT: found a solution, in case someone has a similar problem.
Step 1: I disabled suspending the laptop after closing the lid, as recommended here: How can I tell Ubuntu to do nothing when I close my laptop lid?
Step 2: It is still possible to activate suspend by clicking the turn-off button while holding left ALT-key, as described here: https://www.tecrobust.com/how-to-enable-suspend-button-in-ubuntu/
(technically it probably would work without Step 1, but because of my habit of simply closing the lid to suspend I deactivated it to be sure I don't suspend it this way)
It works, now the laptop does not go back to suspend on its own after I wake it up, but don't ask me why :p
