What if ... ?
Imagine your computer gets a new type of malware that makes it download certain URLs every now and then. Imagine that software creates a special HTTP request with a fake "Referer:" header. Imagine that the purpose of that is to pretend that you are clicking on an advertising link. Imagine that the mentioned links are ads of porno sites. Imagine the software includes an engine to spread itself on your local network. Imagine your boss starts monitoring the employees network activities so you are caught red handed, at least apparently. Imagine that you are fired because of your alleged browsing activities.
Now stop imagining.
It might already happened to one of my clients and his colleague, both fired for the same reason (porn surfing at work) they claim it is wrong because they did not do that. I cannot tell you for sure because their former company is not interested in researching this matter any further.
However, neither the cookies nor the temporal internet files nor the URL patterns they allegedly browsed seemed to make any sense (even if you are a pr0n fanatic). This and the fact they claim they have never used the company laptop for such an activity suggests that the company might have rushed to a conclusion that could be wrong.
For the moment, the ball is on the judge's hands for my client. (But his laptop is not in my hands to further research this possibility). I'll be glad to hear from you in case you may have a clue about the existence of such a software (even if you authored it yourself).