After Installing AwoCoupon Pro I'm having redirect problems

I installed awocoupon pro and now after a customer's credit card has been processed instead of being redirected back to my site they are shown and error message "Order not found! It may have been deleted." This is using chrome.
Using Internet Explorer I can't even get that far, when i add something to the cart and click show cart the cart opens with no products in it.
I've completely uninstalled awocoupon and the problem is still there.
A few days before I installed One Page Checkout coupon but this was working fine. I've now uninstalled awocoupon and one page checkout but the problem is still there
On my C panel i'm getting a lot of errors as well, example: File does not exist: /home/wwwarmys/public_html/clearance, referer: http://www.armysurpluswarehouse.ie/clearance/clearance/reading-glasses-detail.html

Is it a huge co-incidence my site broke after installing awocoupon? Is there anything I can do to fix the problem?


The website is www.armysurpluswarehouse.ie
I'm using Joomla! 2.5.11 and Virtuemart 2.0.22c

Hello,

Seems to me to be a big coincidence. AwoCoupon does not install any hacks into Virtueamart 2.x. And its only interaction with Virtuemart is through the plugin VmCoupon - AwoCoupon. Disabling that plugin is as good as uninstalling it as that is the only bridge to Virtuemart.

It seems you are loosing the session somehow on your site. You should look at the urls fron when its working to when its not. For example, if one url has the www. and the other does not, then that would cause a new session, as those are considered different sites in the session world.