You get the c1.win.c1flexgrid.dll error using Flex Grid Pro 8.0. It happens with a variety of versions of Flex Grid and with a variety of Windows components. Often you get a debugging message that asked you to send the message in the dialog box. Then you have to wait.
Therefore, you are left to look for a faster answer hoping that someone else has had the problem and fixed it so you can get back to work. Good news! They have and you can get back to work!
The problem is a registry error, which is fairly common and easy to fix. What you need is a registry cleaner that can fix this DLL error and many others. ZookaWare PC Cleaner can help you by scanning your registry for all missing, damaged, and corrupted links. Then it will fix it, and you can be on your way.