I defined a custom ComboBox class, called ComboBoxRO, that is derived from the standard ComboBox class and enhances it. I got it working great and incorporated it into 2 different projects.

Now, after a couple of months, for no good reason, it suddenly does not recognize the class in only one of the projects. It was cleanly compiled and checked into sourcesafe several weeks ago, then I just checked out the copy and compiled before attempting to make changes and started getting the error. I have spent a couple of days trying to figure out why the compiler can't find it... the compile generates the message "Type ComboBoxRO does not exist in the namespace...". It is defined in a separate source in the project but under the same namespace as the project. I have tried renaming it (in case it might somehow be conflicting with another type, but it just said that type was not found) and even moving the code into the main program class body and it still does not see it.

Then, I went through the project and changed all other references to the ComboBoxRO to ComboBox and compiled. When I did so, it came back with the message "Type ComboBox not found in the namespace..." even though I do have the "using System.Windows.Forms" defined at the top. Why would it suddenly not be able to see the standard .NET ComboBox any more? How can I fix this so it will compile again?
:(