Two VM - Network of one them fails randomly

[orbegonzo]

I have installed Virtual Box 4.3 12r in Windows 7 64 bits (host has 8GB RAM, i5 2.9GHz). I needed to run 2 virtual machines at the same time, each of them with the same configuration: 3GB Ram, 50GB HD, Oracle Linux 6.3. Machine A has IP 192.168.1.151 and Machine B has IP 192.168.1.156, and in both cases they use the bridge adapter "Realtek PCIe GBE Family Controller".

Machine A works perfect, I can ping the rest of the machines in my LAN, and also access to IPs from outside my network. However, the network behaviour of Machine B is really strange: sometimes I can ping any other machine on the LAN and external IPs, but then, it stops working and I can't ping anything. It happens randomly, and after some time (usualy more than 20 seconds), it starts working again for some time.

I asked in the forums, and after checking the logs, one mod recommended me to make sure I was using the latest version of the network controller, and in case that failed, to create a ticket. I tried removing the network controller and installing it again, but the behaviour is the same.

[orbegonzo]

Log of the first VM (it works ok).

[orbegonzo]

Log of the second VM (it fails randomly)

[orbegonzo]

I have reinstalled Windows from the start, and now it seems that the problem has disappeared; so it seems it was some Windows related issue. Because I suppose that it was a Windows problem, I don't think it's worthwhile to continue to investigate this bug, so I would close this ticket (I would do it personnaly, but I haven't seen the option).