Need help

This is not an error in the signature (or else we'd get much more of them), but a problem of the download, maybe flaky internet connection (might also be on a download mirror side). I've also seen firewalls or proxies blocking .pdb files.

Try to stop the client (exit the Manager), download the file manually from
http://einstein.phys.uwm.edu/download/einstein_S5R2_4.17_windows_intelx86.pdb
into the project directory (usually C:\\Program Files\\BOINC\\projects\\einstein.phys.uwm.edu) and start the Client (or Manager) again.

The filesize should be about 4MB. If it's only a few bytes, it probably only contains an error message from the proxy or similar.

BM