This week, we had an issue with Excel files opening slowly on the network. Some, despite being only 21K over 1000BT, took as much as 5 minutes to open. They opened fine locally.

Someone beat me to posting this on one of the sister sites, but since there are so many fellow system admins here, and I don't see it here also, I thought I would post the question and answer here too. I am sure I will save someone some time.


The problem was the Office File Validation, which was pushed via Windows Update this week. I was able to introduce this problem on a separate network. Removing Office File Validation solves the problem.

This patch was only for Office 2003 and 2007, so 2010 is not affected.


MS KB update: http://support.microsoft.com/kb/2570623

  • I was just going to post about this, but I see you beat me to it. We've been having the same issue here and last night determined it was KB2501584. It seems to be only applying to Excel files; I'm able to open Word and PowerPoint no problem. I can also confirm that Office 2010 is not affected. – Scott Jul 6 '11 at 16:03
  • @Scott I hope you did not spend too much time figuring this out. It could really drive someone crazy if it doesn't just hit you...and the longer someone waits, the less likely they are to make the connection. – KCotreau Jul 6 '11 at 17:23
  • 1
    I'm not sure how much time was spent figuring it out, because it wasn't me personally, but I definitely spent far too much time listening to users complaining about it. :) – Scott Jul 15 '11 at 23:03
  • @Scott Great comment. – KCotreau Jul 16 '11 at 0:09

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