You have a flash uploader and you get this error:

security error: securitySandboxError

This means that the flash is not trusted by the domain and you have to place an xml file in the root of the domain.

The file is called “crossdomain.xml” and this is what should be inside it:

<?xml version=”1.0″?>
<allow-access-from domain=”*” />

Solved! 😉