Originally found here (credit: unknown)

Mr. LaForge, have you had any success with your attempts at finding a weakness in the Borg? And Mr. Data, have you been able to access their command pathways?
Yes, Captain. In fact, we found the answer by searching through our archives on late Twentieth-century computing technology.
Geordi presses a key….a logo appears on the computer screen.
What the hell is Microsoft?
Allow me to explain. We will send this program, for some reason called Windows, through the Borg command pathways. Once inside their root command unit, it will begin consuming system resources at an unstoppable rate.
But the Borg have the ability to adapt. Won’t they alter their processing systems to increase their storage capacity?
Yes, Captain. But when Windows detects this, it creates a new version of itself known as an upgrade. The use of resources increases exponentially with each iteration. The Borg will not be able to adapt quickly enough. Eventually all of their processing ability will be taken over and none will be available for their normal operational functions.
Excellent work. This is even better than that unsolvable geometric shape idea.
. . . . 15 Minutes Later . . .
Captain, we have successfully installed the Windows in the Borg’s command unit. As expected, it immediately consumed 85% of all available resources. However, we have not received any confirmation of the expected upgrade.
Our scanners have picked up an increase in Borg storage and CPU capacity, but we still have no indication of an upgrade to compensate for their increase.
Data, scan the history banks again and determine if there is something we have missed.
Sir, I believe there is a reason for the failure in the upgrade. Apparently the Borg have circumvented that part of the plan by not sending in their registration cards.
Captain, we have no choice. Requesting permission to begin emergency escape sequence 3F!
[excited] Wait, Captain! Their CPU capacity has suddenly dropped to 0% !
Data, what do your scanners show?
[studying displays] Apparently the Borg have found the internal Windows module named Solitaire, and it has used up all available CPU capacity.
Let's wait and see how long this Solitaire can reduce their functionality.
. . . . Two Hours Pass . . .
Geordi, what is the status of the Borg?
As expected, the Borg are attempting to re-engineer to compensate for increased CPU and storage demands, but each time they successfully increase resources I have setup our closest deep space monitor beacon to transmit more Windows modules from something called the Microsoft Fun-Pack.
How much time will that buy us?
Current Borg solution rates allow me to predict an interest time span of 6 more hours.
Captain, another vessel has entered our sector.
This is Admiral Bill Gates of the Microsoft Flagship MONOPOLY. We have positive confirmation of unregistered software in this sector. Surrender all assets and we can avoid any trouble. You have 10 seconds to comply.
The alien ship has just opened its forward hatches and released thousands of humanoid-shaped objects.We'll be
Magnify forward viewer on the alien craft!
My God, Captain! Those are human beings floating straight toward the Borg ship – with no life support suits! How can they survive the tortures of deep space?!
I don’t believe that those are humans, sir. If you will look closer I believe you will see that they are carrying something recognized by twenty-first century man as doeskin leather briefcases, and wearing Armani suits.
[horrified] Lawyers!!
It can’t be. All the Lawyers were rounded up and sent hurtling into the sun in 2017 during the Great Awakening.
True, but apparently some must have survived.
They have surrounded the Borg ship and are covering it with all types of papers.
I believe that is known in ancient vernacular as red tape. It often proves fatal.
They’re tearing the Borg to pieces!
Turn the monitors off, Data, I can’t bear to watch. Even the Borg doesn’t deserve such a gruesome death!
. . . . Two Hours Later, in the briefing room . . .
Where did we go wrong to cause such a hideous catastrophe?
Sir, our archives on late twentieth-century computing technology indicate there was once a challenger to “Windows” on Earth, code-named “Borg.” Later known as “OS/2 for Windows.”
God, you mean this Admiral Gates thought the Borg were his ancient competitors?
It would appear so. But whatever happened to this “OS/2”?
I believe I can help here, Captain. “OS/2” had many of the features of our 24th century computers, but this Admiral Gates successfully gained unusual power from the government through something called a “consent decree.” With it, and a brainwashing technique called “marketing,” he destroyed OS/2 and another competitor called “Macintosh.”
He did this without weapons?
Not quite, Captain. He had an early precursor to our phasers, something called “vaporware.” There is no known defense against this weapon.
Captain, if you’ll excuse me… I’m feeling ill.
Yes, Will, I think we’re all feeling ill. But this incident must serve to warn us and the entire Federation how dangerous it is to awaken this Admiral Gates and his monster “Windows.” Geordi, prepare an emergency report to Starfleet Command. Briefing adjourned