Windows Fax And Scan No Longer Works

We used to use ZetaFax, I'm told. I'm new to the company. We no longer use ZetaFax. Since bringing in Windows Vista Business and Windows 7 Pro computers, and Windows 2008 Server, we now use Windows Fax and Scan.We use Fax Server on the server with quad port RocketModems installed.Now, here's the problem.Some of our employees are having problems using Windows Fax and Scan. The way they use faxing is by finding the file (usually an Adobe Acrobat pdf), open it and then go to the Fax printer.This then auto faxes the document using Windows Fax and Scan.For most of our employees, this works fine.But, suddenly for some it does not work. When I visit the ones who can't fax, I open Windows Fax and Scan and try to launch it. It does not launch. On some of the computers, the user gets a message that the format must be tif. For others, they get a message saying that they can not access to the document folder.I'd like to remove Windows Fax and Scan on these computers and try to reinstall it and see what happens. How can I do that?