Per your post, seems that the DDE function appears to be corrupt. If the issue occurs for all of Office file, please try to repair Office programs or work around it by the following steps:
Go to Control Panel, Folder Options, File Types, scroll down to and select (XLS, XLSx, DOC or DOCx), click Advanced, select Open, click the Edit button. Now uncheck "Use DDE" and then put your cursor on the Application box, arrow all the way to the right and put in "%1" (include the quote marks), If there is a /dde remove it. Then OK your way out. Things should work quickly again.
If it only happens for Excel file, please try this:
Open blank File > Options > Advanced > General Section > Tick the option "Ignore other application that use Dynamic Data Exchange"
Thanks.
