sharing violation

[J]

When I open a excel file, I dont get a message that its
in use. After working in the file, I'll try to save the
change, by using the save button in the toolbar. Upon
saving, I recieve a message that my changes could not be
saved because of a sharing violation.

I never get a message that the file is in use. Can
anyone shed any light on the subject.

Thanks
J