Clearly a very sick machine.
Where do you start?
I had the following info:
- A web application that was working 6 hours before was now failing, without any useful errors in the event log. There was an exit code but I couldn't find any info.
- Diagnosis tools were failing to install
- A colleague was reporting that some apps wouldn't run
My best guess was that some of the operating system was corrupted in some way.
In my extensive research (googling frantically) on this, I came across System File Checker. This runs through all system files and finds any files that might be corrupt.
I also found this rather helpful link that covers how to read the log files.