Look for updated drivers at the Lenovo website.

I resolved this problem by disabling Universal Scrolling for the Firefox application.

Go to Control Panel->Mouse->Lenovo (tab)->Advanced Properties (button)->Wheel (tab)

If "Enable Universal Scrolling" is selected click the Exceptions button and add Firefox to this list.

It might be easier to disable Universal Scrolling altogether, but I do not know how this will affect other applications so I didn't do that.

Neither of the solutions worked for me.

However, I managed to solve the problem: when the scrolling freezes, I roll the mouse wheel while pressed, and press and roll it simultaneously and randomly with right and left mouse buttons. After this fiddling, scrolling is restored.

There is another solution that worked for me, too: try to scroll using the touchpad of your laptop (usually by swiping along its right edge), it also helped in defreezing the mouse wheel.

Thanks very much for the tips. This isn't a laptop, though, so touchpad doesn't apply. It's a desktop running XP x64. I've found that adding the drivers has to be an exact science of mysterious magic. Adding them in the wrong order results in chaos. Also any slight change can throw everything off. But, it's more interesting than having a boring old regular computer that works all the time.

@gridsleep: So what about the drivers? Which version have you got, from where, and in which order have you installed it?

If memory serves, I installed the mouse drivers right after the video drivers which is the first that I install after a fresh OS installation. I just checked and I have the Lenovo drivers 2.1.0.0 for the Scrollpoint Pro Optical mouse, and, surprisingly, the Trackpoint keyboard is using the version 1.0.0.0 drivers installed by the Windows installer as provided to Microsoft by Lenovo. I may try installing the latest Trackpoint keyboard drivers just to see what happens. In any case, I'm still using Opera as my main browser, so the Firefox problem, as Jesse Jackson would say, is moot.

This is still happening as of Firefox 8.0. My drivers are updated. I tried the Universal Scrolling suggestion, but there is no Exceptions button in my mouse suite settings. I note that nor is there a "wheel" tab, and people who keeping referring to it thusly clearly do not have the same device that me and others are griping about. This is a SCROLLPOINT mouse, not a wheel mouse. I cannot find any information which pertains directly to this device; everything is referring to wheel mice. Frustrating.