Windows Form from injected DLL does write/read violation exception

I have a C# dll that I inject into "win32calc.exe", which is working perfectly, I can manipulate space address, hook functions, etc.

But when I want to spawn a Windows Form from the win32calc.exe, sometimes it crashes the application with this Picture of debugger "0xC0000005: Access violation reading location [random address]"

So my guess is that I should manually allocate address for the Windows Form, how would I do that ? Thanks in advance !