I would definitely NOT do that! You both would lose any Paypal or Ebay protection. I would have her call Paypal so they can help her with the issue.
Don't do it. She could pay with a card too?
If she pays that way it will void your ebay buyer and seller guarantee.
^^ I agree with both statements above. Don't do it. It is against eBay policy to complete the transaction outside of eBay. If they find out your selling privileges could be reduced, taken away altogether, or they could ban your account. It doesn't matter if their feedback is 100%- all buyer only accounts have 100% feedback because sellers cannot leave negatives for buyers.
Did she explain what kind of error she was getting? That would help in figuring out what the problem is. I think you can set your Paypal account to deny international/foreign currency payments so maybe double-check your preferences on Paypal to see if that might be the problem? Otherwise, I agree with apanda0622 that she should call Paypal and see if they can help.