try a ping from V1 to V2. If that doesn't resolve check Windows Firewall Settings. if it does try to get the c$ pipe ie:
\\[computername]\c$
if that continues to ask you for correct credentials check your authentication settings on V1 and V2 in your security poicies, specifically refering to LM/NTLM/NTMLv2. Make sure V1 and V2 have the same policies. If they do, set to send LM and NTLM and see if that works. Pathing to policy editor:
Control Panel->System Maintenance->Administrative Tools->Local Security Policies->Security Policies->Network Security: LAN Manager authentication level Properties
If that doesn't work im out :/