I had a pc problem and had to replace HD. When trying to re-install Photoshop Elements I get the message "invalid product key". The version is bought in the shop, product key is mentioned at the back of DVD sleeve. Start with 1057 , but nothing at all.
Did you install from the original DVD? The serial number commencing 1057 will be correct, assuming you originally purchased from a legitimate source. Was this purchase a full version or an upgrade version from an earlier version. If the latter, you will also need the serial number for the earlier full version.