I have had the same problem.. there is alimit to how big the fiel can be. At least in 2000i this is what the help file says:
You paste a Microsoft Excel spreadsheet into AutoCAD, however, the spreadsheet is truncated.
When an Excel spreadsheet is pasted into AutoCAD, only the Picture (metafile) format is used, which can result in the spreadsheet being truncated. This normally occurs when the column width and row height in Excel are set to the default (default width is 8.43, and default height is 12.75), and the pasted object exceeds 18 columns and 70 rows.
Use one or both of these methods to resolve the problem:
In Excel, reduce the column width and row height. You can paste more of the spreadsheet if you reduce the column width and row height.
Paste the spreadsheet in separate parts. By pasting the spreadsheet in separate parts you can break it down into several smaller OLE objects.