What version of Excel is on the two PC's?
It sounds like the new PC does not have MS Excel installed, or has a newer version. The VI probably uses the ActiveX interface of Excel 5.0, which is not compatible with Excel 2000+.
If you don't have Excel, you will need to install it on the new PC. If you install a much newer version, then reconfigure all of the problem method and property nodes. The easiest way is to first change the automation refnums to the current version of the same level. Then select the appropriate property of each of the nodes. Some additional rewiring may be required.