Microsoft Excel abnormal behaviors

Based on the provided information, the behavior is most consistent with Excel becoming unstable or unresponsive due to environmental or configuration factors rather than workbook content or formulas.

Use the following sequence of checks and fixes:

1. Install all latest updates

• Ensure Windows Update and Office updates are fully installed. Updating Microsoft 365/Office and Windows can replace out-of-date files and fix known issues that cause hangs, freezes, or abnormal selection behavior.
• Follow the steps in the article "How to update Microsoft 365 or Office for Windows" referenced from the Excel troubleshooting page.

2. Check whether Excel is busy with another process

• Look at the Excel status bar (bottom of the window) when the issue occurs.
• If it shows that Excel is in use by another process (for example, calculating, updating links, or running another operation), wait for that task to complete before clicking cells or rows. Interacting while Excel is busy can cause delayed or incorrect selection behavior.

3. Investigate workbook content Even though the sheets are not large and do not use formulas, verify that none of the following are present, as they can cause performance or responsiveness issues:

• Formulas referencing entire columns.
• Array formulas with uneven argument sizes.
• Hundreds or thousands of hidden or zero-height/zero-width objects.
• Excessive cell styles from repeated copy/paste between workbooks.
• Excessive or invalid defined names.

4. Check if files are generated or modified by third-party tools

• If any of the affected workbooks were created or modified by third-party applications (for example, reporting tools or export utilities), test the issue with a new workbook created directly in Excel.
• If the issue does not occur in a new, native Excel file, contact the third-party vendor to address possible file-generation problems.

5. Test environmental factors If the above steps do not resolve the problem, test for environmental causes:

a. File location

• Copy an affected workbook to a local drive (for example, Desktop or a local Documents folder) and work from there.
• Avoid working directly from redirected folders, network shares, SharePoint, Webfolders, Remote Desktop/Citrix sessions, or network appliances while testing. This helps determine if the issue is related to network or storage location.

b. Memory and system resources

• Excel workbooks can become large when formatting and shapes are added. Ensure the system has sufficient RAM and meets Office 2021 system requirements.

c. Printers and video drivers

• Excel is printer-intensive and checks the default printer and video drivers when rendering worksheets.
• Temporarily change the default printer to a simple driver such as “Microsoft XPS Document Writer” and test.
• If possible, test with a basic video driver to see whether the issue is related to the graphics driver.

6. Advanced troubleshooting and support If Excel continues to mis-select cells or rows after:

• Updating Office and Windows,
• Verifying that Excel is not busy with another process,
• Checking workbook content,
• Testing with local files, and
• Testing different printer/video drivers,

then the issue is likely environmental and may require deeper investigation. In that case, use the guided support option mentioned in the Excel troubleshooting article or contact Microsoft Support for guided troubleshooting.

References:

• Excel not responding, hangs, freezes or stops working
• Fixes or workarounds for recent issues in Excel for Windows