HELP with giant spiders and Indiana Jones boulder

[Hekai]

I guess I should get more used to forums so I can learn to delete posts I don't want....

In any case, I Googled file integrity, it checked and 18 files needed updating/replacing which the computer/Steam seemed to do on it's own. I checked again and all files were fine.

I exited Steam and restarted it, launched the game from Steam and got a similar "run" pattern. It is like I am creeping along rather than running full speed. Once I did get a fair distance past the bridge before getting crushed but other times I seem to get stuck by an outcrop or something as I try to run, I end up in the outcrop (the wall) or don't even clear the bridge.

I don't mind challenging and having to repeat something multiple times to get it but this seems impossible, Would it help if I downloaded something to video myself playing?

I might also try copying the save file and try on another computer to see if it is my computer's problem. Thanks in advance!