I have not been able to get an update for about a week now. Are there any ides on how to troubleshoot this? I have tried HTTP and FTP.
Failed to validate repository McAfeeHttp. File C:\WINDOWS\TEMP\nai235A.tmp\00000016\delta.ini found hash 392744187759AA084052748F732AB1FF3C4ED2B3, expected hash EA1AD988BE0F5C0FFA666EE1C62B3BC5A175BCED
Do you have anything like a caching proxy in between the ePO server and the download site? It sounds like ePO is being given an older version of the file.
In the short term, you can manually download and check in the ePO package from http://www.mcafee.com/apps/downloads/security_updates/packages.asp - ignore the fact that it says it is only for ePO 3: it works fine with 4.x. That will at least allow you to update your machines while you're investigating the pull task failures.
One thing you can do to see if it's the ePO server causing the issue is to copy the contents of the HTTP or FTP site to a local FTP/HTTP/UNC location within your network, preferable close to the ePO server and specify that as a new source site and try to update from there, if the problem persists then it may be ePO.
Sounds like your license keys or Software Keys may be out of whack. Check your Software/Licensing in the ePO Server. You might also delete and recreate the repository.