Since wiping and reformatting my hard disk the scrolling feature on the mouse has been really odd. The pointer will move around the screen as freely as before, but when I scroll down or use the slider bar the screen shows a ripple effect rather than a smooth roll. The slider jumps up and down the side of the screen.
I thought I might have wrongly installed the driver, so I ran Driver Scan. The slider and mouse operated in perfectly normal fashion on that program's Results screen, but are still odd in every other program.

What mouse?

What software?

What driver?

Some mice have add-on programs and software but should not require them nor drivers.

I'd remove any and all related software and drivers and see how it goes.

It's a Labtec wirless keyboard/mouse combo. I reinstalled with the disk supplied.
Actually, since it's only this function that's erratic, and after a quick surf on the net, I think this may be a problem with the graphics card. I installed that six months ago but the restore I used is about a year old. I would guess that the driver has to be reinstalled on it - something to attend to at home tonight. Managed to lose the driver file from the last update, but there's a fresh one released since then, anyway.

Okay, I admit that was excessive. But I just feel so damned pleased with myself when I can figure out a computer problem and solve it all on my own.
The problem was the graphics card. With the new driver installed we're scrolling smooth as silk.
And tomorrow I get my full-speed internet service back! Oh, frabjous jay!

Thanks for the update. Glad all is well.