The log is saying frames are being dropped from a capture device because the video stream being sent from the device cannot be properly decoded because it is incorrect. One error is no keyframe being set:
I am getting the following errors when decoding H.264 frames received from the remote end of a H.264 based SIP video call. Appreciate any help in understanding there errors. non-existing PPS 0
stackoverflow.com
I'm unsure of the other.
These errors are completely filling your OBS log with repeated entries; they continue as long as OBS is running.
If it's not your capture device, then it's your webcam. Have you tried disconnecting it for troubleshooting purposes?
The only other thing I could suggest would be running as admin, but I'm not sure that will make any difference.
If you've set that device to a mode it supports, then the problem is that it is malfunctioning, and you should seek support from Avermedia.