Error code 0xc0000142 unable to start, unable to reinstall, why?
guigs: Thanks for your suggestion. I don't have any AVG programs on my computer. I'm using Security Essentials, MS Firewall and Malwarebytes.
I'm currently having no problems installing and running other software. Firefox 49, however, will not run.
Looks like the error is that the application is not digitally signed. If its possible that Firefox was not downloaded from an official source, the application could be flagged, but after a reinstall it should update the flag that stops unsigned dlls in windows mentioned: here
Instead of doing the hacky way, please after the clean reinstall that John99 mentioned, try booking the computer in Windows Safe Mode with network support. here's how