weird lines on 2 computers

On my 09 Imac and my new Macbook pro I have constant horizontal lines that run down the screen when opening web pages on Firefox. Does anyone know what may cause this.

That's certainly strange. Since it's happening on both machines and only with Firefox, have you tried removing Firefox, download it again, and re-installing it?

Also does it do it with Safari? Google Chrome?

Weird Lines running down the screen

These lines don't seem to be effecting how the pages work but they are little annoying. I haven't tried removing and reinstalling Firefox and haven't used Safari or Chrome.
Jeff

I get the same thing when I quit Firefox. A single horizontal line of numbers and letters, too fast to read, in the window.
I just marked it up to a glitch in the latest version.

Does it scroll from top to bottom and repeat or is it just one line that runs down and disappears?

Lisa

When I quit, I get a blank white window with 1 line of text/numbers about the top of the page for just a flash, and it's gone.

I don't know what's going on with Mozilla lately, but I have just about given up on all their software. I have to continue using Thunderbird because of its newsreader capability and some NNTP sites that I go to, otherwise I would remove it too.

To the OP: I suggest start using Safari or even Chrome. Safari is stable, and Apple continues to update it for security. Chrome is a bit faster than Safari but also somewhat finicky and it's still only 32 bit.

I have given up on Mozilla and back to Safari using Adblock and Ghostery.