When I add a new coupon code,say for a particular category, all products (from ALL categories) get automatically added in the product name section! AND the category gets Deselected!!!

Even when I remove products (Which is a hell lot of pain,considering more than 1000 products!) and check if my category is properly selected and save the code, all these changes get overridden!
Category gets deselected, all products in database get added to the Product name section and thus the coupon can be used by any buyer for ANY product. While the intention was to only be available for a particular category products!
I am not able to figure out the cause here..can this be a code issue?? or a database issue??

Please help...its driving me crazy and the advertising campaign had to be stopped as none of my discount codes are working correctly.

Thank you very much in advance!
-tarang
EDIT: I found a post in OC1.5.1.3 bug thread about this. But that wasn't a bug, as even if selected categories get deselected automatically, but products added under product name section were only from that particular cat.
But in my case, ALL products in ALL categories get added to the products section, even if only 1 category is selected!
Please please help me.