Lois, when you said "I started renaming my program" did you mean you tried to change the name of the PAF program, or were you trying to change the name of your data files that you use in PAF 4? The data files have the extension ".PAF" while your PAF program is named PAF.EXE. If you can answer those questions, then we can look at the problem.
No, there is no limit on the download of PAF programs from Family Search. You may be just getting a bad connection through your ISP or from Family Search (they are always busy).