If it's any help, here's what I've seen:
1. Using IE7 build 75730
2. When the thread page opens, it opens without error, but the 'insert quote' icon is missing.
3. If you then click on one of the 'quote' icons IE7 will throw an error (discreetly, in the bottom left of the window, saying "Error on page"). Expanding the error gives:
Line 1
Char 319
Unterminated string constant
Code 0