Do you know what the hostname of the Netsight VM is? can you go into the client machine and do a nslookup on that?
for example, if my netsight server is netsight.extremenetworks.com I would type into a command line:
nslookup netsight.extremenetworks.com
and see if the IP resolves correctly.
aside from that have you tried to reboot the netsight server? you can go into the shell (SSH or keyboard/monitor) and type in "reboot".
was the DNS entry updated accordingly?
after you changed the Netsight VM IP, did you restart the server service?
at the top of the server.log file it should tell you the IP that the netsight service is binding to, does that reflect the new IP?