Ayasoftware_SimpleProductPricing
1. Open /app/code/local/Ayasoftware/SimpleProductPricing/Catalog/Model/Product/Type/Configurable/Price.php file and find the following line:
if ($this->strContains($currentUrl, "onestepcheckout/") || $this->strContains($currentUrl, "checkout/cart/") || $this->strContains($currentUrl, "checkout/onepage/") || $this->strContains($currentUrl, "paypal/express/") || $this->strContains($currentUrl, "checkout/multishipping/") || $this->strContains($currentUrl, "authorizenet/directpost_payment") ) {2. Replace it with:
if ($this->strContains($currentUrl, "firecheckout/") || $this->strContains($currentUrl, "onestepcheckout/") || $this->strContains($currentUrl, "checkout/cart/") || $this->strContains($currentUrl, "checkout/onepage/") || $this->strContains($currentUrl, "paypal/express/") || $this->strContains($currentUrl, "checkout/multishipping/") || $this->strContains($currentUrl, "authorizenet/directpost_payment") ) {and save file. 3. Disable compilation mode and clear Magento cache.