DNS error in IE6

[iquito]

Two weeks ago I integrated reCAPTCHA on a website of mine (http://
www.purplemoon.ch), yesterday a user told me he got an error in
Internet Explorer 6 on the page where reCAPTCHA is used. Although I am
in another country than the user I could recreate the problem by just
testing the page with IE6 myself - IE6 gave the error "DNS not found"
when I tried it the very first time, and as no such error occur on any
other page except the reCAPTCHA-page I suspect the problems lies with
reCAPTCHA. The error does not occur with every page request, but it
does happen again from time to time (hard to estimate how often, but
it happened to me at least 10x in 5-10 minutes).

This is strange because the server seems to have no problems getting
the HTML code from reCAPTCHA, and I never experienced these problems
in another browser yet. Is this a known problem? Btw, I'm from Germany
and the other request was made from Switzerland, maybe this is a
"local" European problem?

[iquito]

Now this error occurs on _every_ page request, and only in IE6 - this
seems really serious. Nobody has an idea what could be causing this,
or nobody has experienced this?

[iquito]

I noticed the problem seems to go away when I remove all other
Javascript libraries from my page - maybe the dns error message is
just a typical IE6 error message and therefore totally incorrect. The
problem also does not seem to appear in IE7.

I use the Prototype library (http://www.prototypejs.org/) and a small
amount of own classes and functions - I noticed reCAPTCHA for example
defines its own $-function like Prototype, could there be a
conflicting problem with reCAPTCHA and Prototype used together? Is
there any kind of documentation exactly what kind of functions/
variables reCAPTCHA defines/changes and would it be possible to custom-
change the code somehow?

Some information would be greatly appreciated!

[iquito]

I was able to solve this problem (at least for the time being) with
the suggestions in http://groups.google.com/group/recaptcha/browse_thread/thread/bb6960ac08254376
, the problem is also described in
http://groups.google.com/group/recaptcha/browse_thread/thread/0f24dff9c30d597c
, if anyone happens to stumble onto this problem too. In my case
Prototype + reCAPTCHA did not seem to mix nicely, which resulted in
frequent "dns-errors" in IE6 and IE7, other browsers were not affected.