This error is displayed when Euro Toolbar Add-in is installed because it does not allow us to define a customised toolbar. There are three solutions to this problem:
On installation, do not accept customised toolbar
Unselect Euro toolbar add-in from Tools --> Add-in
Go to Program Files\Microsoft Office\Data\XLStart and delete OMRON CX-Server OPC.xlb file.
On installation, do not accept customised toolbar
Unselect Euro toolbar add-in from Tools --> Add-in
Go to Program Files\Microsoft Office\Data\XLStart and delete OMRON CX-Server OPC.xlb file.