Navigate the the location below in your registry and make the corresponding change.

Create or edit the existing DWORD value (string for Windows 98) named "CacheTimeout" and set it to equal the number of milliseconds to cache NetBIOS names (the minimum is 60,000 - 1 minute). 

Restart Windows.

Key:[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP]
Value Name: CacheTimeout
Data Type: REG_DWORD
Data:Time in milliseconds (Default =360,000)