I have an absolutely bizarre problem with my computer

[Egnever]

44. Interesting

so it is often triggered by clicking in a text field?

Some things I would look for. First and foremost batteries make sure they are good on both. I would also look at speaker placement. some speakers throw off a ton of interference. If they have an on off try turning them off for a while and see if the issue goes away.

Two wireless dongles close together can also cause issues, maybe try moving one to the back of the machine.

I don't know who makes you mouse or keyboard in my experience Logitech keyboards and mice are rock solid and come in a variety of price points. Most of their dongles can work with multiple devices now days as well regardless of if they were packaged together.

The spaces being inserted leads me to believe it is interference of some kind that is causing it to misinterpret signals causing mouse movement to be interpreted as keystrokes. Are your keyboard and mouse from different manufacturers?

I would be very surprised if it was your computer as it seems to have persisted from machine to machine. That makes it almost certain it is one of the peripherals causing it.

Good luck ghosts like that can be very difficult to track down cause they are hard to reproduce with any sort of consistency.