Thank you! Not many people can provide that level of detail about their equipment! It certainly makes our job MUCH easier when someone can give us everything we need in one post like that. Again, thank you!
I don't remember specifically what was in SP3, but there was some security stuff that was added. So, let's assume that putting on SP3 has changed something in your network.
OK, back to the problem. Yes, the DHCP Client Table is what I was talking about. Your menu is a bit different than mine (WRT150N) which shows my client table under the status button, but that's OK. We'll work around it.
The key points I picked out of your post were: (1) [i]DHCP server is enabled. Beginning IP address is 192.168.1.2 & ending address is 192.168.1.254.[/i] Then, you said, prior to SP3: [i]"I had the connection between the computers working but not the workgroup. [u]I just mapped the ip addresses and sharenames[/u] and voila'."[/i] And now, you say: [i]"I can see the workgroup, but I get this permission error."[/i] You also said your client table now shows: [i]"a non-existent laptop at the address 192.168.1.2 with a non-existent mac address."[/i] But, you did NOT say IF the client table shows the two laptops along with that non-existent laptop.
And, in your original post, you said both laptops had internet access which means they are connecting to the router. They should both be listed in the client table, but their IP address may well have changed, so your IP mapping may need to be redone. So, first thing you need to do is to disconnect from your existing IP mapping. On each laptop, go to My Computer, right click the mapped drive(s) which point to the other laptop and choose Disconnect. In a subsequent post, you said you set static IP addresses on each laptop, but you have the DHCP server turned on. Set each laptop to obtain its IP address automatically (dynamic). Reboot each computer and wait for them to completely boot back up again.
I am going to assume here that after running the wizard on each computer your workgroup is still called [b]BRASTED[/b] and the computers are still named [b]Scott[/b] and [b]Joyce[/b]. You will need to know the share names on each computer.
Now, remap from [b]Scott[/b] to [b]Joyce[/b] using the path \\joyce\sharename ... but, before you click the OK button, click the Log On Using link and provide the Windows Logon credentials for the user on [b]Joyce[/b]. For example, if the user [i]Joyce[/i] usually logs on to the computer named [b]Joyce[/b], provide her Windows logon credentials for her. Do the same, but reversed on [b]Joyce[/b] mapping back to [b]Scott[/b] using \\scott\sharename as the path and providing [i]Scott][/i]'s Windows log on credentials.
Conversely, you can simply create a user account on each computer which matches the Windows log on credentials of the other computer (i.e. create a user named Scott on the computer named Joyce and match Scott's Windows log on credentials from the Scott computer.) But, that only saves you from having to use the 'Log On As' link when mapping.
Give that a go and let us know how it turns out.