>When I compile classlib I get the message "memo file ...vct is missing or is invalid". But I can edit and update any class of this vcx, it seems that nothing is wrong, only when I try to generate the .exe or issue compile classlib.

Are you issuing the Compile command from the command window? If so, check to see that you are compiling the same classlib you opened with the class browser (check the drive/path). You may have a ClassLib.vcx file sitting in a different directory that does not have the ClassLib.vct file that the compiler is trying to compile.