jQuery auto expanding textareas acting strange

I have tried various different jQuery autogrow/expand text area plugins, and they all work good and well on the demo page but for some reason whenever I implement them into my existing site, they act very strange, this is what is happening:

It works great, if you're manually typing in text and hitting enter after every line, however, if I copy and paste a large block of text in, 开发者_运维问答for some reason it consistently chops about 30% off the end, and it's simply cut off, no scroll bar, just cut off.

Even if i refresh the page (with the text staying in there) it still cuts it off. I'm guessing some JS/CSS is conflicting but I have no clue what it could be!

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1. Which plugins have you tried so far?
2. If you use Firebug, try and monitor the textarea for changes. See what it does to the value and the height of the textarea
3. Set the height of the textarea to 1000px and see if it can handle the 'copy/paste' and show you the whole thing.