CAPTCHA’s text input box is working on Internet Explorer, but not with Firefox. I cannot enter the code.

This is a well-known issue caused by misusing the <label> element. Make sure you are using it correctly.

This is good:

[captchac your-captcha]
<label>Enter the code: [captchar your-captcha]</label>

This will not work correctly:

<label>[captchac your-captcha]
Enter the code: [captchar your-captcha]</label>

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