I have just update to civicrm 4.7.8 But now i have a weird problem on contribution when order are made with paypal. Several contribution are created and one are refunded. This issue is for all new contribution payed by paypal. You can see that the total of the contribution is 0. Could you please help me ?
This may not be specific to PayPal - I think it may be related to a bug that has been resolved in the latest release candidate:
Should not be long before it's out.
Here's the JIRA issue on that: https://issues.civicrm.org/jira/plugins/servlet/mobile#issue/CRM-18661