I was happily pinging in the net when suddenly:

Pinging X with 32 bytes of data:

Reply from .235: bytes=32 time=1444ms TTL=41
Reply from .235: bytes=32 time=1767ms TTL=41
Reply from .235: bytes=32 time=1531ms TTL=41
Reply from .235: bytes=32 time=-1198187ms TTL=41

Ping statistics for .235:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 1444ms, Maximum = -1198187ms, Average = 1073443462ms

A negative time for the reply. I checked wireshark and it had the same values:

Time delta from previous displayed frame: -1198.187867000 seconds
Time since reference or first frame: -1179.935038000 seconds

I didn't change the time of the machine while pinging. This was made in my local network at home, from a XP VM in windows 7. So I blame the VM (virtualbox). But I was wondering if this strange behaviour (to me) could have a reason, or if any of you have seen this before. Thank you bye.