For myself, I can't remember a time when a mouse cost more than an hour of an IT guy's time.
I suppose a good office-computer mouse in 1990 would cost $100 ~ $200 (say $350 today). In that case, yes troubleshooting it for a day would make sense, especially if it's not an isolated problem.
> For myself, I can't remember a time when a mouse cost more than an hour of an IT guy's time.
This is not a sensible comparison to make. Support staff have a lot of free time. They have to, because they're support staff -- if they were always busy, then whenever a problem arose, it would be impossible to get support.
So to have the IT department playing with the mouse is unlikely to cost the company anything. If something comes in that's more important, the mouse problem will be put aside. If they have nothing better to do, they can play with the mouse.