[jQuery] undefined ret[0] error

[jQuery] undefined ret[0] error

Im not sure whats causing it, but on my blogging script i am writing with jQuery, i get this error message, seemingly at random times...
<blockquote style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;" class="gmail_quote">
Warning: reference to undefined property ret[0]
Source File: <app folder>/jQuery.js
Line: 477
</blockquote>
The error is happening:
<blockquote style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;" class="gmail_quote">
<blockquote>if ( ret && ret[0] == context ) ret.shift(); //here
  done = $.merge( done, ret );
  return done;
</blockquote></blockquote>In the function $.Select
Most of my app is written using jQuery and the AJAX plugin, and that error seems to popup randomly, but appears alot more if i refresh the page instead of just clicking go...
Also when i see that message, parts of my page fail to load. The more times i get that error, the more parts that fail.
I would usually be able to fix stuff like this, but for some reason i cant seem to track it down...
Any help would be appreciated.
Thanks!
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