I had the same problem and figured it out from a post on another site. 
Search your javascript include files to see if you have a function 
called "prompt" in one of them. I removed the function since I wasn't 
using it and then my prompt worked fine. you could also rename the 
function.

> I don't know why it happens, but try with window.prompt();
> 
> 
> /Robert
> 
> 
> -----Original Message-----
> From: Alex Bienz(viplondon) [mailto:alex@v...] 
> Sent: den 27 november 2001 10:38
> To: javascript
> Subject: [javascript] Re: problem with the prompt box
> 
> 
> Ok the browser I'm using is IE 5.5 sp2 and I've seen these boxes work 
fine
> before on other examples.
> 
> The code I'm using for the button is...
> 
> <input type="button" name="Button" value="Button" onClick='prompt("Enter 
an
> email address.", "")'>
> 
> There isn't really any other code I can think of that would interfere 
with
> this button or the code inside!?
> 
> > -----Original Message-----
> > From: Imar Spaanjaars [mailto:Imar@S...]
> > Sent: 26 November, 2001 6:59 PM
> > To: javascript
> > Subject: [javascript] Re: problem with the prompt box
> >
> >
> > Hi Alex,
> >
> > What browser are you using? This works (as it should) fine on
> > my machine.
> >
> > It may help if you post some more code, including the button
> > declaration.
> > Maybe something else is causing the problem.....
> >
> >
> > Imar
> >
> >
> >
> >
> > > Hi there, here's a good one for you problem solving
> > javascript guru's
> > >
> > > I've got a simple asp page with a button that when clicked
> > runs this
> > code...
> > >
> > > onClick='prompt("Enter an email address.", "")'
> > >
> > > Now when I click the button instead of getting a prompt box
> > appearing as
> > I
> > > would expect I get the text 'Enter an email address' written in the
> > status
> > > bar at the bottom left of my browser!?
> > >
> > > am I missing something elementary here?
> > >
> > > 		Cheers,
> > > 			Alex.
> > >
> > >
> > $subst('Email.Unsub')
> >
> >
> 
>