check sum test failed message while upgrading dc12 software

[Goshe]

I was downloading software to dc12 when I get this message (Checksum test failed!) for IPS file that had to be downloaded (actually the file was downloaded and did not pass the checking). I was downloading file by file.I am upgrading to 11503 software. Also tried with files from another software versions and always get this message only for ips file

Any suggestions?