Ideally, QL should be installed onto the same drive as Excel, however, after moving files & changing hard drives etc, you should always take the time to redefine your links.

If this still does not solve your problems, you could try these suggestions:
1. Re-install QL onto the same drive as your Excel
2. Reinitialize your data dictionaries
3. Always remember: Load & Save your worksheets using QL's Load & Save options, NOT Excel's

Refer to Chapter 1, Page 1-12+ in the QL manual on Redefining your Excel links, and page 2-4 explains more about when to reinitialize your data.

That should be all that is required.