PROXYHOST.EXE - why is it UPLOADING data to Core?

LDMS8.8

I got a call from one of our buildings that their network was running really slow.  I tracked it down to a single machine - it had uploaded almost 4GB of data to our Core server.  While it was uploading, I ran NBTSTAT -B to find out what process was connected to the Core, and it was Proxyhost.  I killed the EXE and the bandwidth use ceased.  Then a few seconds later when Proxyhost was re-started, it immediately started uploading to the Core again...

Any ideas?  What/how exactly does Proxyhost.exe do?

Thanks!