Two things might be happening here.

First, when you have the Ctrl key down, scrolling the mouse wheel will zoom the text larger or smaller.

Second, when you click the mouse wheel, a circle appears with little directional triangles on it. When you move the mouse pointer above the circle, the page scrolls up, and when you move the mouse pointer below the circle, the page scrolls down.

I think you are talking about the first one. It should only happen when you are holding the Ctrl key down, unless something has changed in Firefox's settings.

To edit or reset your mouse wheel actions, you can use the about:config preferences pane. (Please note that an add-on might be able to override these settings, so if these don't work, you should check your add-ons.)

(1) Type or paste about:config in the address bar and press Enter (click the button promising to be careful, and please do be careful!)

(2) In the filter box, type or paste wheel and pause until the preferences are filtered

Now you can reset any changed preferences (shown in bold) to their defaults, or you can change them to suit your preferences. The names can be hard to pick out, but here is what you should see:

Wheel alone

• Name = mousewheel.withnokey.action
• Default = 0 (scroll)
• Scroll default = 6 lines (Name = mousewheel.withnokey.numlines)

Alt+Wheel

• Name = mousewheel.withaltkey.action
• Default = 0 (scroll)
• Scroll default = 1 lines (Name = mousewheel.withaltkey.numlines)

Ctrl+Wheel

• Name = mousewheel.withcontrolkey.action
• Default = 3 (zoom text)
• To disable: change to match one of the actions you like better

Shift+Wheel

• Name = mousewheel.withshiftkey.action
• Default = 2 (Back / Forward in history)
• My Recommendation: change to 1 (page up / page down)

All wheel configurations are at default. I am not holding the Ctrl or Alt keys down when this happens. The wheel on my mouse is click-able and when I'm scrolling a web page and accidentally click the roller on my mouse, a magnifying glass icon shows up and the page starts zooming in and out because I have scrolled several times before I realize the zoom has been activated. This only happens in Firefox and only since I've upgraded to 4.0.1

Did you check the settings in the Control Panel > Mouse ?

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

Checked Mouse settings first. The only option for wheel is how far to scroll for each notch. Tried your suggestion of starting in safe mode. With all my Add-ons turned off I still got the magnifying glass when I clicked the roller on my mouse.

What else ya got?

Well, I found the answer to my question. In my Control Panel there is a file named Mouse Suite. In there I can re-assign what the roller wheel does. I selected "other" then the function "none". Problem solved! Thanks for taking the time to look into this for me. Maybe this will help someone else who runs across the same issue.

Can you pls tell the solution for the second problem i.e.: when you click the mouse wheel, a circle appears with little directional triangles on it. When you move the mouse pointer above the circle, the page scrolls up, and when you move the mouse pointer below the circle, the page scrolls down.

@loverspoint4, if you click it again, that should cancel that function.

Were you trying to click a link? When you click on a link using the wheel (or middle mouse button) it should open in a new tab.

That circle with the 4 points on it is autoscroll, and if you do not like it, you can disable it. The setting is in Options/Preferences > Advanced > General.