Can't install Easy Social

Hi. I've tried to install Easy Social v1.2.19 Joomla 3 onto a Joomla 3.3.1 site both by way of url and by file upload but both fail at Step 4 in the process - all good up until then. When I try to install it by way of file upload I get a limited error message saying I should contact support and when I try to upload it directly by url I get a more detailed error message, saying ' The MD5 hash of the download file does not match. Please contact support for help.'

Can you help please?

Thanks

Jamie