tedster - 8:38 pm on Oct 2, 2011 (gmt 0)
I can't see how presence or absence of external links, in itself, could be a factor. No external links? I know sites that were hit by Panda and many more that weren't. Lots of external links? Same thing. Just a few external links? Ditto.
The quality of pages that you link to "might" be an issue, and the motivation behind your internal linking as well (are they really helpful for visitors, or are they there just to push PR around?) But I personally would not look in this area for helpful fixes at all.