HI

Do you have any event driven macros in the worksheet?
If so, in the immediate window of the VBE type
Application.EnableEvents = False     and press Enter

Then carry out your deletions or clearing.

When you have finished go back to the VBE and type.
Application.EnableEvents = True     and press Enter

try hilighting 1 colum at a time and delete that it might be a bit time
consuming but it will eventually clear the sheet
or you could run a macro to clear several rows at a time

try this , but it will only delete if there are no cells protected/ hidden
the macro will delete 20 rows at a time, and loops 10 times deleting a max
of 1000 rows
(if you find this soloution works or you have to amended it please post it
to the group for all to see - thanks)

Sub DELROWS()
'
' DELROWS Macro
'
   myNum = 10                  ' you can change this value but not to high
   counter = 0

   Do While myNum > counter
       myNum = myNum
      counter = counter + 1
'
   Rows("1:20").Select        ' selects top 20 rows you can change this
value also
   Selection.Delete Shift:=xlUp
Loop
End Sub