File Sharing between 7 and XP

I have suddenly lost the ability to share between a laptop running Windows 7 Home Premium 64 and a desktop running XP Home Sp3. It worked fine up to a week ago, and I haven't made any changes...but perhaps some updates automatically loaded.

Here's where I am:

Network Places on the Desktop does not show the Laptop. I am able to access the internet and shared folders on other network computers.

The Network view on the Laptop shows the Desktop, but if I click on it I get an error message that says "Windows cannot access \\Desktop". I am able to access the internet and shared folders on other network computers.

I'm running McAfee Total Protection, and I have tried disabling the firewall on both machines, but that hasn't solved the problem. McAfee on each machine sees the other machine in the My Network view, and each is a trusted machine.

Both machines are set up for the same workgroup.

Ideas for restoring this functionality?

Thanks Roderunner. Unfortunately, this doesn't exactly address my situation. I want to be able to write from the Windows7 Laptop to a shared folder on the XP Desktop (which I am using for a backup).

FWIW, I did try the steps outlined in the document, though I was unable to find a Run prompt on the XP machine. I did try using a command prompt (DOS lookalike), but the XP Desktop could not find the 7 Laptop. It didn't make any difference as far as I can tell.

Thanks. However, the settings described in the article are what I already have in place.

Nope, neither system is password protected, nor are the shared files.

Thanks for the suggestion, but there has to be a better solution. It worked up to a week ago with no password. Hard to believe I have to add a password to make it work, and I don't want to hassle with passwords every time I turn the systems on.