This is the second time this has happened in three weeks.  No one can get into Evo.  When they double click the icon, nothing happens (an evoerp.exe instance does appear in Task Manager, but that's it).  The Pervasive System Analyzer can't connect via name or IP: it doesn't get past "Trying to use named pipe to resolve name to address".  I can, however, run Evo locally on the server.  Whatever the problem is also seems to be affecting NetBEUI (it takes a long time for Windows Explorer to populate  with all my pc names on computers with a mapped drive to the "problem" server).
 
I can ping the server by either name or IP.
 
I have 35 users who can't work...and I'm out of ideas.  Last time it happened, I rebooted the server, which took upwards of 1.5 hours ("installing updates; do not shut down").  Once I had rebooted, it was fine...until now.

After a grueling 13 hour day on the phone with MS, Symantec, and HP, we determined that we had faulty/outdated drivers on various components.  Updated the chipset, NIC, and SATA controller.  Also upgraded Symantec EP from 11.0.2000 to 11.0.5 and reseated the RAM chips.  One or more of those has hopefully fixed the locking up.  Server is an HP ML150 G5 running Server '08 x64.
 
A special Thank-You to Lori, who got me through the last hour or so, helping me move the install to a working server.  Thanks again, Lori!