Lightroom :: Composite TIFF Image From Two Raw Files - Can't See Imported File?

I'm having  a problem seeing a file in LR 4.2 when it is in the folder where I want it to be.
 
I created a composite tiff image from two raw files that reside in two different folders.  I had exported the two raw files from LR as tiffs,  opened the tiffs in Photoshop CS5,  then combined them into a multi-layer tiff to create a 600+MB  composite file.  That composite was saved in Photoshop under a new file name using "Save As" .  I knew the new composite file would not be in the LR catalog until I imported it.   When I imported, the image went into a new date-named folder (call it folder "A").  So far, it all made sense to me.
 
From this point on things got funny.  Working within LR, I tried to move the uniquely named composite from folder A into the folder that one of the component files came from (call it folder "B").  The Move failed. Instead, I got an error message saying the file already existed in "B."   I could not see the file in "B" using lightroom, but MS Explorer revealed that the file was indeed there.  I don't understand how it got there.
 
Still trying to get my composite in "B" recognized by LR, I first deleted the composite from "B" using explorer, then went into LR and moved the file from "A" (where LR recognized it), into "B".   Still no good.  LR does not show the file in "B", yet it appears in explorer.
 
I suppose I could live with this composite file in its own folder, "A," but that is not really where I want it.  More importantly, I don't understand why I can't see it in LR in the folder where i want it.
 
- Is my catalog file damaged?
-Might the XMP files have anything to do with this?
-Is the size of the file (>600MB) a factor?

Win 7, LR 4.2, PS CS5.