Well I can come up with a couple of explainations.
1> The names are already used. To verify this open a command prompt and type nslookup . this will tell you the ip addresses of all the computers with this name. To solve this rename the computer.
2>DNS list is wrong. To solve this go to command prompt and type ipconfig /flushdns and try again.
3>IP conflict. if your using DHCP this should not be a problem.
Also a better way to deal with these type of remote installations is to statically assign IP addresses, then use the ip address to log onto that computer. This does not require DNS resolution and therefore is more acurate.
Good Luck with your problem
ddanonimity