Playback is jittery

I have a big problem and i am hoping someone has a solution.
Backstory

My main laptop died ( I know motherboard died) So i took out the hard drives of the main laptop and put them into my backup laptop BOTH ARE HP ENVY
Yes i have editted before on the backup laptop.

Working with 1080i

But now when i play back footage to edit it is jittery slow or non exsistant. Audio plays fine
it plays at 9 fps then goes 40 then to 29.97 but video doesn't move.

i have watched many youtube videos on the playback settings but nothing seems to work.
changed timeline settings nothing change project settings. i know it is something stupid i am missing

it is one of those setting you do once and never touch it again

i have 29.97 footage THree cameras none of the camera settings have been changed

ok who can prove how stupid i am

thanks in advance

well after a lots of changing things i found teh problem
it happenes that this laptop has 2 video cards installed and one was fighting with the other.
so i just disabled one and it worked finee

wow who knew