The most common reason why people think a good CID is banned is because CCAPI is spoofing an old CID even after you save a new CID in Webman Setup. Try uninstalling CCAPI by clicking on the homebrew and following the prompts until it asks you to uninstall. Then, press R2 + CIRCLE on the XMB (PS3 Home Screen) and you'll see your IDPS appear in the top right corner. When it appears, check that the IDPS LV2 matches your new CID. If so, try signing in.