It would seem you use a particular .Net component and that might have trouble under Windows 7 for some reasons. It could be either a problem in the .Net component itself or possibly the fact that it was not written for the .Net version that is on your PC. You definitely will have to take this up with the manufacturer of that .Net document as they are the only ones who can tell you more about the compatibility of their software with particular Windows and .Net versions.
The next step of action would be to use a C# written test application to load the component on that machine and execute the same operations.