Windows 7 Filesharing issues

Im currently running Windows 7 build 7600 ver 090713-1255 x64. I've configured my Windows 7 homegroup with other PCs in the network on my Thomson Speedtouch 585 v6 router.. The PC also has Nod32 Antivirus 4 and this is all running on wired connections..
In Networking advanced settings, I've set:

• turn on network discovery
• turn on file and printer sharing
• turn on sharing so anyone with network access can read and write files
• enable media streaming
• enable file sharing for devices with 40-56bit encryption
• Turn off password protected sharing
• Allow Windows to manage homegroup connections

I have also designated static IP addresses to both PCs, however on the Win7 Machine only for IPv4 as I don't think my router supports IPv6.

Now everything works fine at first. I can view and access files from both my Winxp sp3 Machine and Win7.. The mayhem starts when I actually start accessing the files. This was also tested with Ubuntu 9.04 on a samba share, resulting in the exact same problem.
First of all, I tried transferring files resulting with woeful speeds (2-4mb\per second!), all of a sudden the connection drops out, I can't access the shared drives anymore and Windows 7 gets these irregular stutters affecting everything from music to mouse movement! This also happens whenever I try to access files such as viewing videos or music from both ways, they run okay for a few and then freeze and Win7 goes stutter-crazy...

I really don't understand what's the deal, I thought this homegroup thing was supposed to provide less problems and more solutions; but hey its Microsoft were dealin with here.. I'm not sure what to do next, should I disable IPv6? or does anybody familiar with this problem have a workaround?
Thanks for reading, would appreciate the help

I thought only Windows 7 supported homegroups. I completely disabled homegroups and just set up my sharing the old fashioned way. I haven't had any issues except for sometimes my only XP machine will lose access to the shares on one of the 7 machines every few days. Rebooting that specific 7 box seems to fix it. Other than that, it's solid and the speed is where it should be.

how do you disable homegroups and set up networks the old way? I dont see any option in Win7..

I disabled homegroups, viewed a few vids but still the problem is there the pc stutters and goes nuts and I have to restart..

I set it up the same way I did in XP. Right-click on the HDD in Win Explorer and choose Properties. Select the Sharing tab and click on Advanced Sharing. Tell it to share the drive and name it what you want (the name will actually be "<name you input> on COMPUTERNAME", i.e. mine is named "C" and shows up on the network as "C on Comp1". After naming it, click on "Permissions". I just let it be "everyone" because there isn't anybody on our network but the family. Select the permissions you want at the bottom (full/read/write), hit apply & ok. Hit apply & ok again in the naming window, then you're done. Should be able to access it from any computer on the network, but you will need the username & password you entered upon logging into Win7.

Ive already done that, the files and access work fine, only for a few moments, then the stutter comes into effect and i lose access..!

Very strange. I haven't run into that at all. What is causing the stuttering? Is your HDD just constantly accessing and causing the system to be sluggish?

I have no idea, this problem sometimes takes a while or sometimes just seconds into accessing a shared video or audio file. But as soon as it does, Windows 7 starts the stutter and the internet connection starts dipping and losing access so I'm guessing this is related to my built-in Ethernet driver which was honestly running fine until this whole Win7 fiasco. Anybody got a clue?, still cant share files..