Error when combining pngs into a pdf. All pngs say "File skipped."

I'm combining about 48 pngs. Their file size is admittedly large, around 25-30mb each. Every time i combine them, one by one they all get the same error "file skipped." I've read a bunch of posts and none of them helped. Right now, I'm trying to uninstall and reinstall Acrobat, but it keeps saying "Installation failed." (Repeatedly. I've retryed many many times. I have a very good internet connection.) 

Before uninstalling, i tried just combining a few images, and images that were much smaller, with the same result. 

I'm about to try the web version. Looking for help.