When you open a Microsoft Word document when connected to a network, it may take longer than expected to open if the document has a template attached or linked and one of the following conditions is true:
• The attached template, its folder, or its share is missing.
• The attached template has been moved.
• The attached template has been renamed.
• A linked file referenced by the document is missing, has been moved or renamed.
When a Word template is missing, Windows will try to locate the missing template multiple times. The process of locating a missing template may cause a Word document to take longer than expected to open.

In your case, the template is 'missing' because it's inaccessible via the client's network. If the document doesn't need to be linked to that template, the simplest workaround is to re-attach it to Word's Normal template before distributing it. Alternatively, simply disconnecting from any networks, including the internet, while opening the file can improve performance.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]