Clear Windows 7 network computer names cache

You need to clear both the DNS and NetBIOS name caches. According to the Microsoft support article Microsoft TCP/IP Host Name Resolution Order both are used in Windows to cache hostnames.

Do this from an elevated Command Prompt by running these two commands:

ipconfig /flushdns
nbtstat -R

(The -R is case-sensitive)

If you're still having trouble, double-check the Windows Hosts file to ensure a static name mapping hasn't been configured. On Windows NT and above the hosts file is located in the folder %Systemroot%\System32\Drivers\Etc and is named hosts (without a file extension).

In Command Prompt run ipconfig /flushdns