Windows 7: In Windows 7 Can't Open Files Across Network

I have 3 machines all running Windows 7. Machine C & D are running Windows 7 Home Premium 32 and Machine A is running Win 7 Business Premium 64. To start I setup a Homegroup and joined everyone to it. I can open files on B & C via Machine A and I can open files on B via C and C via B, but when I try to open files on A via B or C, I can see the file, but when I try to access it the system freezes and does not open it.

A little history:

Machine B is an older install of Windows 7. Machine B is a fairly new install. Both have very little "extra" programs on them except for anti-virus. Machine A has a new install replacing the the old install from the ground up as of yesterday of Win 7, has anti-virus that is the same variety as the others.

I have tried disabling the firewall on Machine A, did not work. I have tired disabling the anti-virus, did not work. I have even tried sharing a new folder outside the Homegroup and once again the other computer can see everything in it, they just freeze when I try to open anything. All the computers are on the same Workgroup. Machine A is running a gigabit adapter and the others are sitting at only 100/10 and are hardwired to the system.



All of the machines have updated Microsoft software and NO hacked or stolen software. All have been scanned for malware and the anti-virus is up to date.

I am perplexed and puzzled as to why Machine A can access the other two with zero issues and open files and the other two can see, but cannot open files on Machine A. This has to be something real simple and I am not seeing it.

G

Since the original post I have reset the permissions on the Machine A drive that is having issues as lined out in the Microsoft Support page How to use Xcacls.exe to modify NTFS permissions. This appears to have kind of fixed the issue of opening, now it is just a matter of speed. There is a latency issue of epic proportions when trying to open even the smallest file from Machine A compared to Machine A opening one on the other two machines. Machine A can instantly open a huge file and it takes up to a 3 minutes to open a small file stored on Machine A via the other two machines.

After waiting it finally appears.

We have ran a PING via CMD and the machines all have equal up/down access so it is not a network issue.


So now we can open a file on the B & C machines, but it takes forever and the A Machine opens the exact same files on B & C instantly. Where does this put me other than even more confused?

Unless this is security essentials I'd have to place the blame on the anti virus software. The problem is that the only way to find out is to uninstall the A/V software completely using it's special tool.

We have disabled all A/V software and once again using Machine A to read and write to Machine B&C is wicked fast, but trying to read or write to machine A from either B or C is a nightmare.

Someone in passing mentioned that the issue could be a network problem with the Gigaport card on machine A and the cards or switches in the system. Thoughts?

Machine A appears to be the problem machine in that case.

If the problem seems to be isolated to just a single machine then yes I would check into the network adaptor, maybe reinstall the drivers or reset TCP/IP stack etc.