Cannot share files between 2 laptops

OK, I'm a VBA programmer, been programming for 30 odd years, but I cannot get our two laptops sharing a Public folder.
I have a Vista machine, fully updated. The other machine is an emachine with Windows 7 starter, again fully updated. We have one internet connection in the flat that is connected to the Landlords router to which I do not have access. I got a Dlink hub (8 port desktop switch), both laptops are connected to that and the hub to the internet point. Both laptops have internet no problems at all, but neither laptop can see the other one. I've even pinged each others IP addresses and they just time out.
They both have the network set as private/home, they both have network discovery on, public folder sharing on, password protection off. The public folder on the vista machine has sharing on and Everyone having full control. Workgroup name is the same on both machines. The vista machine calls the network - Network 10 and the other machine calls it Network, but I can't find a way to change that if it's a factor. Windows Firewall is off on both machines. Comodo Firewall is on but I quit that on both machines and it didn't make any difference - so I assume that isn't the problem. Each machine can see itself under Network but that is it.
Any ideas, anyone?

a) what "below" and b) I'm not turning off my firewall and antivirus, why would I have to.

Again what "below" and again I'm not turning off my firewall. You are beginning to worry me? You've said nothing of use yet, all you've done is post adverts for .pst file repairs as far as I can see!!!

Try this link, you may want to consider that Comodo is causing this problem in which case reconfiguring the firewall or uninstalling it may be best.
Sharing files and printers with different versions of Windows - Help & How-to - Microsoft Windows