When I try to start my '02 Windstar, I get a single loud clunk as the starter tries to engage. The engine won't spin. Also, I can't put the transmission into neutral. The shifter moves easily but nothing seems to happen in the tranny. It's an automatic transmission, so everything should not be locked up together, but it is. Do I have a torque converter problem?

 

You might just have a starter that is starting to go bad. They can just clunk once as you describe. As for the shifter moving easily, there may be a linkage problem somewhere causing the linkage to be loose.

 

There have been problems with the converter flexplate breaking. Inspection cover /starter removal may be able to confirm if the plate has broken and locking the engine from turning.