I get:

"A script on this page may be busy, or it may have stopped responding.

You can stop the script now, open the script in the debugger, or let

the script continue."

With the code:

$('div:has("p+p')')

And the HTML:

<div><p>1</p></div>

This worked fine with jQuery 1.2.6.

Test case: http://jsbin.com/atiha/edit

Tested in FF3, IE7 and Chrome.