If you set calculation to manual before opening, you can try this code to get rid of unused ranges:
<font face=Tahoma><SPAN style="color:#00007F">Sub</SPAN> WorkbookReducer()
<SPAN style="color:#007F00">'From: http://www.contextures.com/xlfaqApp.html#Unused</SPAN>
<SPAN style="color:#007F00">' Re-set used range</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> myLastRow <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>, myLastCol <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> wks <SPAN style="color:#00007F">As</SPAN> Worksheet
<SPAN style="color:#00007F">Dim</SPAN> dummyRng <SPAN style="color:#00007F">As</SPAN> Range
<SPAN style="color:#00007F">For</SPAN> <SPAN style="color:#00007F">Each</SPAN> wks <SPAN style="color:#00007F">In</SPAN> ActiveWorkbook.Worksheets
<SPAN style="color:#00007F">With</SPAN> wks
.Activate
<SPAN style="color:#007F00">'.Unprotect "bigdog"</SPAN>
myLastRow = 0
myLastCol = 0
<SPAN style="color:#00007F">Set</SPAN> dummyRng = .UsedRange
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">Resume</SPAN> <SPAN style="color:#00007F">Next</SPAN>
myLastRow = _
.Cells.Find("*", after:=.Cells(1), _
LookIn:=xlFormulas, lookat:=xlWhole, _
searchdirection:=xlPrevious, _
searchorder:=xlByRows).Row
myLastCol = _
.Cells.Find("*", after:=.Cells(1), _
LookIn:=xlFormulas, lookat:=xlWhole, _
searchdirection:=xlPrevious, _
searchorder:=xlByColumns).Column
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">GoTo</SPAN> 0
<SPAN style="color:#00007F">If</SPAN> myLastRow * myLastCol = 0 <SPAN style="color:#00007F">Then</SPAN>
.Columns.Delete
<SPAN style="color:#00007F">Else</SPAN>
.Range(.Cells(myLastRow + 1, 1), _
.Cells(.Rows.Count, 1)).EntireRow.Delete
.Range(.Cells(1, myLastCol + 1), _
.Cells(1, .Columns.Count)).EntireColumn.Delete
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">If</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">With</SPAN>
<SPAN style="color:#007F00">'.Protect "bigdog"</SPAN>
<SPAN style="color:#00007F">Next</SPAN> wks
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN></FONT>
If that doesn't work, your wb may very well be corrupt.
HTH,
Smitty