Copying a whole work sheet into a protected work sheet issue

• I have a worksheet set up that I need to import data into
• The cells in the import sheet are all unlocked and not hidden
• The work sheet is protected with ‘Select locked cells’ and ‘Select unlocked cells’ “ticked”
• I need to protect the sheet as I do not want any rows or columns added or removed
• I copy data from source sheet and can past if:
• I select any number of cells
• Select all Columns
• Select all rows

However when I copy the whole sheet by going to top left hand side of sheet (Click the Select All button.) or I use CTR+C and paste into the protected sheet Excel becomes “Not responding” and I need to close it down
The above procedure does work when the sheet is not protected

Can anyone advise re how to overcome this issue as the sheet will be used by different users who are likely to use the CTR+A function?
Thanks in advance