In 2010, one of my client employee kept complaining the report she downloaded from our intranet app couldn't be opened.

It was only her machine. It worked on all others.

I looked at the file, and it was a tad smaller than on the other machines.

I disabled her anti-virus, it worked !

Realizing kaspersky was taking a bite at the report, I created a self signed tls certificate so the anti virus could read it.

Worked.