AutoCAD Civil 3D :: Pipe Network Data Reference Error

I have a major error currently affecting my work that I need to resolve ASAP. I'm using C3D 2012 64 bit with Windows 7. I have multiple model drawings that I have created pipe networks and view frame groups in, and using those model drawings I have created plan and profile sheets from the view frames. I created data shortcuts of all my pipe networks and referenced the pipe networks into my sheet drawings. In the sheet drawings I drew the network parts into the profiles, and everything displayed exactly as it was supposed to. No issues at all.

Now fast forward about a month. Out of the blue one day I open one of my sheet drawings to perform some edits and notice that the pipes that were previously displayed in the profile views showing inside and outside walls with the centerline turned off now show up as a simple line. I haven't changed any settings at all. I looked at the properties of the pipes, and they seem to have all ignored their asigned diameters- the pipe data in the referenced network now assumes all inverts & crowns are the same elevation as the centerline.

Long story short, I have gone so far as to completely reinstall the program and restart the drawings, but the more I edit the oringal network the worse the problem gets. Now all of my structures are attaching themselves to the surface profile instead of the pipes, and the entire network gets put onto my current layer rather than the layers I assign in the Create Pipe Network Reference dialog box.

It happens to any drawing I try to open on this network- even ones created by third parties that I haven't edited. And the problem resides in the drawing because anyone I send the drawings to has the same problem. It will even crash the entire program sometimes when they try to open my drawings.

Civil 3D 2012 SP3 - Windows 7 64 bit - Intel Core i3-2120 - 8 GB Memory