You need to set a registry entry.
HKEY_LOCAL_MACHINE\SOFTWARE\Business Objects\Suite 11.0\Crystal Reports\DatabaseOptions\LOV
If you are using R2, then change 11.0 to 11.5.
Add a string called MaxRowsetRecords and set a new maximium number of records. Making it 0 gives you unlimited records.
I cover how to do this and give you many other tips and tricks for working with parameters in Chapter 4 of my book
Crystal Reports Encyclopedia.