screen font size

hi,
     i am working on a CAD program written in Delphi 2.0 .I have a problem
when i run my system in large fonts 125 dpi ie 120 pixelsperinch setting .
the program does not do anything ,it never shows any drawing in the drawing
area specified by the program . Now if i open the project and then all forms
one by one and re-build all the project and then run the executable it works
perfectly But now this Exe does not work when the system fonts as Small
fonts ie 96 pixelsperinch and shows the same problem . Can anyone tell me if
i am missing something . The drawing is taken by the following routines
Windows.Polyline(dc,.....);
Windows.SetPixel(dc,....);
Windows.MovetoEx(dc,...);
Windows.Lineto(dc,.....);

On the drawing command i placed a message dialog for showing me
pixelsperinch . On different font sizes it shows the correct pixelsperinch
value .

Your help would be really appreciated

Thanking you
---------------
Devinder