If you are signing in with your nine-digit authorization, try signing in with your WorldShare ILL account, or vice versa.
This could also be a browser caching issue. Try signing in to the Policies Directory in a private or incognito tab, going directly to https://illpolicies.oclc.org instead of using a bookmark.
If you are still receiving this error consistently, verify that you are using the same IP address for the duration of your connection with OCLC. If your IP address changes in the middle of your session, this could cause a client reset, breaking your connection to OCLC and causing errors such as this. You may need to check with your IT department to adjust your firewall settings in this case.
If none of the above steps fix the issue, contact OCLC Support with your OCLC Symbol, IP address, and a link to this article.