Fixing a Magento processing orders Error - Sagepay 3D Auth

We're using Magento 1.9.1.0

When customers enter all details for card payment, the page seems to freeze or take very long to process the transaction up to 3-4 minutes as some customers closes the page - We are getting this error which we are not sure how to fix :
2007 : Please redirect your customer to the ACSURL, passing the MD and PaReq.

If you have come across this before and able to fix it for us please contact me ASAP.

Also, a number of customers complaining that the site crashes as they are checking out so I can only assume an issue with Order saving process as per the discussion on sagepay forum here: http://ebizmarts.com/forums/topics/view/4524/10

Specific technologies required: Magento 1.9.1.0 and ebizmarts (SagePay Extension)

(Please note that remote access will be granted to work on this as no login details will be provided)

Please feel free to forward your bid to me.

Thank you