I've got a strange issue at home that has been bugging me for weeks, but I really need to get it sorted now so I'll detail as much as I can and hopefully someone can spot what might might be wrong.

I have a wireless router connected to the internet and 3 devices connected to it. They are:

Name    OS           Network     IPv4
PC1    Windows 7    WORKGROUP   192.168.2.2
LAPTOP1   Vista     WORKGROUP   192.168.2.3
PS3                             192.168.2.4

and they all get their IP addresses dynamically.

Both PC1 and LAPTOP1 can ping PS3 and get a response. PC1 and LAPTOP1 are unable to ping each other by ip address unless I ping by their name (which bizarrely shows that it is pinging via the IPv6 address). Also, to confirm this both PC1 and LAPTOP1 can ping each other via the long IPv6 address that they both have so they can obviously see each other just not via IPv4. I've disabled the firewalls on both machines as well to rule that out.

I don't really know what IPv6 is used for and I've tried disabling it on both machines but all that happens then is that neither machine can see each other at all then. Does anyone have any idea of what may be stopping them seeing each other, any ways I can look at fixing this, or any network tools that may help identify where it is failing?

Thanks,
Mark