checkout continue buttons disabled if you modify in IE

Hi. Using 1.5.0.5 and came across this. During checkout, if you get to step 6 and click Modify on either step 4 or 5, the continue button is disabled and you cannot continue. It works fine in FF 8, Chrome 15, but not IE 9 (I think my customer uses IE 8 and they discovered it).

I haven't made any significant changes to the checkout process. Any ideas? Has anyone else run into this? Thanks!

Any fix for this?

Nervermind, fixed it myself-.