An attempt has been made to use one of the reserved unit names, such as System, as the name of a user-created unit. 

The names in the following list are currently reserved by the compiler.

• System
• SysInit

unit System;
interface
implementation
begin
end.

The name of the unit in this example is illegal because it is reserved for use by the compiler.

unit MySystem;
interface
implementation
begin
end.

The only solution to this problem is to use a different name for the unit.