Hi there! It sounds like you accidentally grouped some cells in your Excel file, which caused the [Group] tag to be added to the file name. Don't worry, this is a common issue and can be easily fixed.

To remove the grouping and get rid of the [Group] tag in the file name, follow these steps:

1. Open the Excel file that has the [Group] tag in the file name.
2. Look for the grouped cells. They will be highlighted with a thick border and a small bracket icon in the top left corner.
3. Click on the "Ungroup" button in the "Data" tab of the ribbon. This will ungroup the cells and remove the thick border and bracket icon.
4. Save the file again with a new name that does not include the [Group] tag.

Once you have completed these steps, you should be able to switch between tab pages and work in the file without any issues. If you have any other questions or concerns, feel free to ask!