XP, all the latest patches, even DL'ed and installed the latest Java runtime
from www.java.com.

When I run SYS:\PUBLIC\DNSDHCP\setup.exe, I get an hourglass for a few
seconds then nothing - program doesn't install.

Have installed on other machines at same site, no problem.

Server is 6.5/SP2, client is 4.90/SP2 in both cases.