charts are disappearing upon scrolling

Dear all,

I am trying to create a summary spread sheet for several data. On this spread sheet I am placing tables and charts underneath.
The number of pages on this sheet is mounting upto 50 pages.
After pasting charts from different workbooks into this spreadsheet, some charts disappears completely, others have only the frame of the chart showing, and all charts drift and change location or appear in a different place than where it was placed.

If I put on print preview, I can see all charts, but still dislocated and they disappear when I switch to normal mode.

Many Thanks in advance.
M.