Shopping Cart Error - URGENT HELP NEEDED - ot_category_discount.php

I have just noticed that there is an error message when products are added to shopping cart on my site. I am not sure how long it has been there but I suspect a few weeks as my conversion rate has been going down in that time.The message says:

E_WARNING: Line: 285 File:/includes/modules/order_total/ot_category_discount.php; reset(): Passed variable is not an array or object
E_WARNING: Line: 286 File:/includes/modules/order_total/ot_category_discount.php; Variable passed to each() is not an array or object

I changed my hosting a few weeks back and am wondering if this may have happened then.

I am completely clueless about the technical stuff but if there is an easy fix to this I'd appreciate any pointers.

thanks.

What discount contribution did you use?

What is your domain?

It also appears that problem can occur when using an older version of Zencart with PHP5, which your new host is probably using.

What Zencart version are you running?