Lets say I opened an excel file(A.xlsx) from any folder in drive c: And I am working on it. And at the middle of the work I wanted to open another existing excel file(B.xlsx) in another folder in drive c: . Lets say I click on the file B.xlsx and did not opened it. So it is selected situation but not opened. Then when I go back to file A.xlsx , it is not allowing to make any entry to any cell. If I go back and remove my selection for file B, by clicking on another any folder, I am able to work on file A.xls.
But some time it is not doing it, that is strange.