Can't copy files from win7 laptop to Win7 Desktop

Help!

I've been searching all over for solutions and can't come up with a fix. I've tried this (Access denied to my files on another PC)

and this How to Share File with Group and User Permissions in Windows XP

and this How do I get round Windows 7's file permissions? - Microsoft Answers

and this Change workgroup name in Windows 7?

but I can't seem to get it to work.

I have 3 pc's in my network. I've networked win2k machines with win98, 95, and XP, but this one has me stumped.

Machine 1 - Dell 2.66 running win7 32 bit. (M1)
Machine 2 - Generic 1.8 running win7 32 bit. (M2)
Machine 3 - HP i3-2310M CPU @ 2.10GHz running win7 64 bit (M3)

They're all Home Premium. I can push or pull files from M1 to M2 and visa versa. But I cannot pull or push between M1 and M3. After several hours this morning I was able to have M3 pull from M2, but I could not push and I could not get M2 to push or pull from M3.

I am at wits end. I have no idea why I was able to get M3 to pull from M2...all machines have the same settings.

The error I get when pushing or pulling is:



Can someone please help me. I'm not opposed to rechecking everything, perhaps it's something small, but I've been trying to get this to work for weeks and can't seem to figure it out on my own. I wish they' would have left things alone with the networking like win2k.

Also, quick note, the workgroup name and the network name are the same...don't know if that has anything to do with it. Thanks!

Maniwar:
Hello and welcome to the forum.
Generally these types of issues have one or two things in common.
1. Over zealous or misconfigured third party firewall product (Comodo or ZoneAlarm, etc.,) of third party internet security suite (AVG, AVAST, McAfee, Norton, you name it) Consider removing any such third party product and replacing with the built in Windows 7 Firewall and Microsoft Security Essentials much more networking friendly and you can always re-install what ever you want later once the issue is resolved.
2. User name and or password issues. Be sure that you are either using the same user name and password across all platforms or minimally the source machine has the same account information (username and password) with appropriate permission as the username and password you are using on the destination machine.
Finally try switching the network type from home to work, sometimes that helps, don't ask me why.
Regards
Randy