How to eliminate isolated PRVs with infinites coordinates?

Hello!

I have a problem with my network that is imported from GIS-based file. Among the network elements, PRVs have no coordiantes (indicated as -infinites). When I zoom extend on PRVs, I see: X:NaN m, Y:NaN m). But on other layout compenents (pipe, Tank, etc.) every thing is ok. 

When I compute the model, for all those isolated valves, I got error messages ad following: Donwstream pipe is undefined.!!

What is the origine of my problem?

Futhermore, I found that all elements I previously deleted are found in infinite being in isolate elements.

Thank you in adavnce,

Gashin