I don't know when or why it happened, but I am only getting a red X where the image should be.

When I did the test (ubbthreads.php?ubb=captcha&t=im&test=1) suggested by Rick, I received the following error message:

PHP error: sh: /home/maritim5/www/forums/images/captcha/backgrounds/background1.jpg: cannot execute binary file

I am still using the 7.4 final version.

Any thoughts on what is happening on my end?

Are you using GD2 or imagemagick.
Possibly the host upgraded and moved imagemagick to a different path.
Try GD2 and see if it works again.

It looks like maybe your path to convert isn't set, or was blanked out. In the control panel under Db, Paths & Urls -> Paths & Urls you'll see where it wants the path to convert, which should be something like:

/usr/local/bin/convert

I am using GD2 only, therefore, does the following still apply?

/usr/local/bin/convert

I don't think it still applies, as I think the above is for IM and not GD2

GD2 was working OK back in February, however, for some reason it is no longer showing the image, but only a red X.

Maybe that test, shown below, was only for IM, therefore, do you have a test for GD2?

ubbthreads.php?ubb=captcha&t=im&test=1

As a quick test you have two background images for captcha.
background1.jpg
background2.jpg
One is I will call a smooth background and the other rough.
Whatever your path is to the two files you should be able to view them with your browser. That will at least tell you the files are there and okay.
So it would be like http://www.yoursite/forums/images/captcha/backgrounds/background1.jpg
This will at least test the image files. The letters images on the background are another thing.

ubbthreads.php?ubb=captcha&t=gd&test=1

I to have been having the same issues
Then I run that line I get

"page_captcha_run not found! Please contact the site administrator!"

Looking to trouble shoot myself as I jst got told about it, if I find the solution I will post.

If anyone else knows the solution, please do the same.

Thanks

That looks like maybe a script problem. I'd check your scripts/captcha.inc.php and make sure it's complete.