It's in your Firefox profile folder:
SYSTEM_ROOT\Documents and Settings\USER_NAME\Application Data\Mozilla\Firefox\Profiles\GIBBERISH.PROFILE_NAME
If it doesn't exist, you'll have to create it. Just open a text file in a text editor and save it using the name 'user.js'.
Insert these lines:
user_pref("capability.policy.policynames", "noalert");
user_pref("capability.policy.noalert.sites", "http://www.annoyingalert.com");
user_pref("capability.policy.noalert.Window.alert", "noAccess");
Replace the annoyalert.com site with the name of your site. Save the file.
Close and restart Firefox.
More info:
http://www.mozilla.org/projects/security/components/ConfigPolicy.htmlhttp://www.mozilla.org/unix/customizing.htmlThis should work IF... it's a Javascript ALERT prompt you're talking about. The prefs script above will disable it. In Javascript, an ALERT merely pauses script execution until you click OK, then it'll fall through to the next line, which should be the redirect to the question page.
If it's a CONFIRM prompt (a 2-button OK and CANCEL dialog) however, this method won't work. The action following a CONFIRM is conditional, depending on which button you click. Making the CONFIRM go away will stop the script and the redirect will never happen. To fix that, you'll probably need to write a
GreaseMonkey script, which is way more trouble than this is worth.