This is normal a hidden workbook that you use to store macros
that you want to use in all your workbooks

You can hide it like this

When you open Excel and you see PERSONAL.XLS(B) in the title bar you can use this to hide it.

Excel 97-2003: Window>Hide
Excel 2007     : On the View tab in the window group choose Hide

Then close Excel and say Yes to save the changes to your PERSONAL file.

Depending on whether or not you're on a network, the folder where the
PERSONAL.XLS file resides in either of the following folders:

Network
C:\Documents and Settings\UserID\Application Data\Microsoft\Excel\XLSTART

Where UserID is your network login id.  

Local:
C:\Documents and Settings\Application Data\Microsoft\Excel\XLSTART

Open My Computer or the Windows Explorer, locate the correct directory and
delte the file.