Fatal Error: Cannot redeclare vm_ps_coupon::remove_coupon_code_vm()

We had around 28,000 coupons and recently uploaded 20,000 more. Initially we encountered out of memory errors while trying to work with coupons in the admin area so we doubled the memory allocated to PHP. This fixed the issue.

However, now customers are unable to use their coupons when checking out. They get the following error.

Fatal error: Cannot redeclare vm_ps_coupon::remove_coupon_code_vm() in /home/spexonth/public_html/administrator/components/com_virtuemart/classes/ps_coupon.php on line 141--

We've tried everything, from verifying the data in the jos_awocoupon and jos_awocoupon_manufacturer tables to restoring the old data.

We have thousands of Living Social customers emailing us that they can't check out.

Any ideas? A Google and Bing search produce nothing when I search for the error above.

TIA

Since we are under the gun, we're offering a nice donation to whoever solves our problem.

Yes, the problem is in the file
/home/spexonth/public_html/administrator/components/com_virtuemart/classes/ps_coupon.php

It seems that is has been corrupted somehow. Can you pm the code from that file? Or if you prefer, send me a private message with ftp access and I can look at it directly.