We recently fixed a problem a business was having with very slow connections to their Excel files when attempting to connect to them through their network. This specific situation was dealing with Microsoft Office 2003, but could have the same effect with other versions.
Problem: Slow access across the network when attempting to open Excel files.
Solution: Uninstall Microsoft Office File Validation Add-in (KB2501584) from the installed applications/updates.
This is in the same place you uninstall other software from your computer. After removing File Validation all Excel files opened very quick and without delay. Hopefully this can help anyone else that may have ran into this problem.
What is file validation? here is an excerpt from Microsoft “Office File Validation is a security add-in for Office 2003 and 2007. Office File Validation is used to validate that Binary File Format files conform to the Microsoft Office File Format. The user will be notified of possible security risks if files fail to conform to the format.”
If you don’t have to open files you are unfamiliar with then everything will be fine. If you download excel files from the web or are being sent files from others through email then you should either use caution in opening files or leave the add-in installed.