How do I unlock 'personal.xls' in Excel?

[Mammoth]

I have somehow set up Excel such that, whenever I try to open an Excel file
from Windows Explorer, I am given a dialog box telling me that 'file in use;
personal.xls is locked for editing'. When I click any of the 3 radio
buttons, the file opens, but in a new window with no connection to open Excel
windows (e.g., recently used file list is different). Any idea how to
disable this 'personal.xls' locking?

 

[Dave Peterson]

Maybe one of these:

http://contextures.com/xlfaqApp.html#AlreadyOpen
or
http://contextures.com/xlfaqApp.html#ReadOnly

Both from Debra Dalgleish's site.