Unable to push large files onto network drive

This is my set up. I have my PC running Windows 7, connected through wireless to the internet and my home network via Apple Airport Extreme. I have a harddrive connected to the Airport Extreme acting as a network drive.

I can see the network drive, and I pull files of all sizes from it, but I have not been able to push large files to it. I can push smaller files to it with no issues (so far success with up to 706MB). I tried pushing a 1.4GB video file to it and it keeps giving me the error message: "There is a problem accessing A:\ Make sure you are connected to the network and try again"


I have an iMac hooked up to the network. I can push the same 1.4GB video file from my PC to the iMac over the wireless network. I just cannot push it onto the network harddrive. While I have no problems pushing large files onto the network harddrive from my iMac.


So in summary:
Pushing large files from PC to network harddrive - Failed
Pushing large files from PC to iMac - Success
Pushing large files from iMac to network harddrive - Success


I've tried most of the proposed solutions I found on the internet.
I've turned off the firewall - no change.
I've turned off my anti-virus - no change.
I've tried disabling autotuning - no change.
I've turned of the power setting on my network adapters - no change.
I've turned off the Remote Differential Compression - no change.
I've tried the file transfer in Safe Mode - no change.


So what is the problem here and what else can I try????