We recommend you repair the Office 2007 programs first. This can help to restore the following registry key which affects the behavior of opening .xlsx file: HKEY_CLASSES_ROOT\Excel.Sheet.12\shell\Open\command
If the issue persists, you can compare the same registry key with a known good machine that uses the same OS and Office version. Then correct the key manually.
Important Before you modify the registry key, please backup the registry.
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