How easy is it to damage an IBM CGA display?

All is well - the industrial CGA display is happy being connected to a real CGA card. It's quite the looker too. People at the office are impressed, possibly not in a good way. ;-0 The machine (a 5160) has the monochrome adapter (Hercules), a genuine CGA card, a 3Com 3C503, memory, serial, floppy and a hard disk controller. It has 512KB of RAM and a full height 10MB hard disk. NCSA Telnet *was* running on before I put the CGA card in. (I had a Cirrus Logic VGA card in it yesterday.) Now NCSA Telnet is hanging on startup after reading it's config file. I'm having a hard time believing that the CGA card replacing the VGA card broke it, so I'm going to have to undo my changes and try again. My own TCP/IP still works, so I know it's not a hardware conflict. (It's pretty hard to get CGA to conflict with anything.) Mike