Checking & Making Visual C# Project installable

Hi. I need help with a small c# Project. I have coded a small winform apllication, which runs perfect on my machine (Win8). On Win7 an exception will be thrown, when i open a second form (saves settings) with 3 textfields for url, username and password. Because the apps has only 2 WebBrowsers, i guess that the probelm is not the code. I guess that the problem are the project-settings. The job: 1. Im sending you my projectfolder 2. Your job is to fix the exception, so that the application runs 100% on Windows 7 and XP too. 3. You make the application installable ( with .Net 4 check etc...) You must send me a folder with installation data and the projectfolder for visual studio. In the attachments you can find the full code (about 130 Lines only) and the exception. Please check it before... The project must be finished today (Friday 30.11.2012).