1. Using Windows Update, update Windows to 2004 or 20H2/09 per
https://obsproject.com/blog/five-simple-tips-for-new-streamers
2. Install the newest 64-bit version from
https://obsproject.com/download
3. Run OBS as admin (right click on short cut, Properties, [Advanced...], Check box for 'Run as administrator', [OK], [Apply], [OK]
4. Display and Game Capture Sources interfere with each other. Never put them in the same scene.
If still having issues then see
Depending on your Windows version and what sources you wish to use, you may need to set OBS to run on a specific GPU. Not sure which Windows version you have? Press Windows+R and run "winver". For Windows 10 1909 or newer: Open Settings and search for "Graphics Settings". Select "Classic App"...
obsproject.com
If still having issues then
1) Restart OBS admin.
2) Start your stream/recording for about 30 seconds. Make sure you replicate any issues as best you can, which means having any games/apps open and captured, etc.
3) Stop your stream/recording.
4) Select Help > Log Files > Upload Current Log File. Send that link via this troubleshooting tool or whichever support chat you are using.