Browser dialogs (Alert, Confirm, & Prompt) not longer working in Internet Explorer & Firefox on a specific Windows install

Question

I have a particular install of Windows 7 that will not display the standard JavaScript dialogs from web browsers.

e.g. These all fail, regardless how they are called on any site.

javascript:alert('A message and an OK button');
javascript:confirm('A message and an OK & Cancel button');
javascript:prompt('A message, an input box & an OK & Cancel button', 'Default');

The code itself is correct and not the issue. It works just fine on any other Windows PC in any browser... as well as in Google Chrome on the affected machine (since Chrome renders it's own dialogs vs. depending on the Windows built in dialogs)

My presumption is that there is a setting somewhere in Windows that is blocking or overriding the display of these dialogs - I just have no clue what it is or where it is.

Although not related I should note that all of the browsers on this PC have their Popup Blocker (for browser window popups) turned off.

Answer 1

Affecting both Microsoft Internet Explorer and Firefox seems highly unlikely to happen by accident, because they are completely separate implementations. (For fun, you could also try Google Chrome.)

The most likely reason I can think of is some sort of "anti-virus" protection software affecting the behaviors of these browsers.

(The next-most-likely reason I can think of is someone disabling JavaScript support, manually, in both browsers.)

Answer 2

Check under Internet option --> Security Tab --> select custom level --> In the Security Settings window which just opened Enable all under section 'Scripting' and 'Activex Contorls and plug-ins'

Answer 3

I had this problem using a Windows 8 tablet running IE 10 and solved it by Enabling 'Allow websites to prompt for information using scripted windows' option under Internet Options -> Security Tab -> Custom Level