So, you go to open a file in Civil3D... only to find that the file open dialog box doesn't open.  Instead, it asks you to enter the file name manually.  Now, in the good old days, that'd be possible.  C:\CAD\filename.dwg.

These days the directories are a tad bit longer.  S:\department\civil\project\2011\etc...\filename.dwg Makes manually entering a bit of a hassle.   So what gives?  Why isn't it showing the dialog box?

The answer is that somehow the Filedia value became 0 instead of 1.   Who knows how?

To fix this, enter the command filedia and when it prompts you to enter a value (it should say the current value is 0), enter a value of 1.   Then try to open a file.  The dialog box should open and all should be right with the world, for at least a moment.