Send parameter / Controls dissapearing!?

I need to know who to send a parameter to another program..

Example: on any file on your desktop, and choose to 'zip' the file. The file's location gets sent as a parameter to WinZip, or WinRar respecably.

My issue is similar, except I need to send an integer from 1 application, opening the 2nd app with the parameter.

I have tryed building a class, and defining the parameter within the Public ClassName(int Index) constructor which worked, but for some reason all of my controls erased from my form!:(

After getting my controls erased SEVERAL times from new classes, I tryed building another WindowsApplication.... Same issue.

I guess this is a 2 part question :)-
1. How to pass parameters accross apps
2. Why do my controls erase!!!???

I have used vb6, VB.NET, C# for about 4 years now, and I havn't run into the issue (nor have I had to pass parameters this way).

Any and all help would be GREATLY appreciated! :)

Thanks in advance