I inadvertently posted this to the end of a preceding thread. I have downloaded VMSpc24b2_Install.exe on two separate PC's, using two separate downloads. One machine is a Dell Inspiron, the other is a Dell Latitude. Both running Win XP Pro, one with SR2, the other with SR3. The VMSpc installed with no problems, no error windows on each. Each time the program is started I get an "Error Reading File" box that states... Caterpillar 3126 250 has failed to load properly. Torque and Horsepower readings may be inaccurate. I click OK, and the program continues into the default screen and runs properly. This occurs on both notebooks. For test, I downloaded VMSpc versions 2.2 and 2.3b4 from your site. They both do not exhibit the above error upon start up. I even substituted the four 3126 data files from 2.2 into 2.4. Still the same result. The JIB is not connected. Just running programs on PCs. Any ideas? A related question: I have a Detroit Diesel Series 50 engine. I notice you have data files for Series 40 and 60 engines, but no Series 50. Why is that? Can I reliably substitute another engine file in place of the missing Series 50 listing? Thank you.