ProgressBar issue on other monitor

I am developing a Windows app with C++Builder. When a ProgressBar is launched, it works perfect reaching 100%. If I open the same app with the same OS (Windows 7) on other PC (only difference is the monitor), the ProgressBar reaches 50% or 75% where would it must go to 100%. Where could be the issue?

for(contador = 0; contador <= 100; contador++)
{
   ProgressBar1->Position = contador;
   Sleep(10);
   Application->ProcessMessages();
}