If you are experiencing a white screen when trying to log into the United Airlines website, and you have already cleared your cache and cookies, follow these steps to troubleshoot and potentially resolve the issue:

1. Try a Different Browser: Test logging into the United Airlines website using a different web browser to determine if the issue is browser-specific. Good alternatives include Firefox, Chrome, or Safari.

2. Disable Browser Extensions: Sometimes, browser extensions can interfere with website functionality. Disable all browser extensions and try logging in again.

3. Reset Browser Settings: Consider resetting your browser settings to default. This can resolve issues related to misconfigured settings that might be causing the white screen.

4. Check for JavaScript: Ensure that JavaScript is enabled in your browser. The United Airlines website may require JavaScript to function properly. If it’s disabled, follow browser-specific instructions to enable it.

5. Test in Private Browsing Mode: Open a private or incognito window in your browser and try logging in from there. This mode does not use extensions and often bypasses cached data that could be causing the issue.

6. Check Internet Connection: Make sure you have a reliable internet connection, as poor connectivity can lead to incomplete page loading.

7. Look for Updates: Ensure that your browser is up to date. Older versions can sometimes lead to compatibility issues.

8. Review United Airlines Support Resources: Consult community forums or the United Airlines help center for additional troubleshooting tips, as others may have experienced and resolved similar issues - learn more - learn more - learn more.

If the problem persists after trying these steps, it may be a temporary issue with the United Airlines website itself. You can also reach out to their customer support for further assistance.