Pivot table changes the name of a value

[MMGroup]

Excel 2003, Windows XP.
Dataset:
Account Type
Account Name
Amount

Pivot Table:
Left Hand column:
Account Type
Account Name
Data section: Sum of Amount

Account Names consist of some 50 unique names.
This pivot table has been working properly for several years.
Suddenly, one of the Account Names appears in the Pivot Table with a completely different name! Changing all entries of the account name to some other value changes the Pivot Table to the new value. Changing all entries of the account name back to the original name causes the pivot table to show the original completely different name.

I've moved the file to another computer running Excel 2003 and the problem is replicated.

My first thought was there was a NAME value, however there are no NAMEs defined (Insert : Name : Define)

Got me stumped.

 

[MMGroup]

Solved the problem

I tried something I didn't expect to work, but it did. If one types over the Account Name value on the Pivot Table, Excel remembers it. I simply typed over the displayed value with the desired value. I guess it makes sense, just had never thought I could change that.