This might or might not help.
(Optional but recommended) Unplug mouse and receiver, if applicable. (do the rest through your keyboard/trackpad/touchscreen or another mouse if you can)
(Optional but recommended) Turn off and remove batteries from mouse and receiver, if applicable. This is to make sure there isn't some sort of internal memory in the mouse that would remember its config with whatever bugs it might entail.
Remove all drivers and software related to this mouse.
Reboot computer.
Make sure 5 minutes have passed since the pieces are without their batteries, if applicable.
(Put batteries back in/turn on and) plug receiver back in, if applicable, and wait for Windows to install the driver on its own.
Put batteries back in/turn on/plug mouse, and wait for Windows to install the driver on its own.
Do that "sync" or "connect" thing that receivers and mice often have, if applicable, where you have to press a button on each piece.
See if your buttons work properly.
If not...
If it still doesn't work, try one last reboot. If it's not fixed, then I have no idea how to help you.
Thanks Ariane. Unfortunately this didn't work. This is a wired mouse and goes into a switchbox. It worked the other day - and I don't know if a MS update came through or what. But now it's broken on all computers in the switchbox. Seems like I'll have to try hardwired direct to one of the computers and if that works; then diagnose if the switchbox is faulty. Weird that just that functionality wouldn't work. <sigh>. – user187053 – 2013-01-11T00:39:03.463
What's a switchbox? Do you mean a USB hub? Edit: If really this is super important to you, you could see if you have a system restoration point from back when you know your mouse worked. – Ariane – 2013-01-11T00:40:38.527
By switchbox, I am referring to a KVM switch (with KVM being an abbreviation for "keyboard, video and mouse") - it's a hardware device that allows a user to control multiple computers from one or more[1] keyboard, video monitor and mouse. Yea - I think I'm going to have to do some more diagnosing as I won't have an option to uninstall any MS updates. I'm suspecting it's hardware related. argh. – user187053 – 2013-01-11T00:56:52.143
Oh. If I had known you had such a special configuration, I would have told you to try without that piece of equiment before anything else. – Ariane – 2013-01-11T00:57:57.493
yea - but it's worked for years just fine. Gotta crawl under the desk I guess. Thanks so much for your help - it does seem like it's hardware actually and not software. – user187053 – 2013-01-11T00:59:18.190
Things that have worked for years have all the more of a reason to cease working at some point. :p Good luck with the crawling. – Ariane – 2013-01-11T01:02:53.410