Rohan online : Multiple Clients Issue with 64-Bit Operating Systems

The reason why 64-bit is important:

I used to run 3 (sometimes 4, if the Loader.exe let me) clients on my computer, but it was not very playable (laggy) because I was reaching my maximum memory (3-4 Gigabytes because of the 32-bit Operating System).

To solve this, I first tried overclocking my CPU from 3.0 GHZ to 4.2 GHZ, but the memory was still bottle-necking the performance of my computer with the clients. Next, I thought to upgrade my computer's memory to 8 Gigabytes, which would require a 64-bit Operating System. So, I upgraded to the free Windows7 OS that Microsoft has available for the next year, and bought 4 more gigabytes of RAM. After installing the new computer setup, my computer was able to easily start up and run the 3-4 clients, without any lag at all.... but it turns out that each would eventualty get a Memory Exception or randomly freeze (anywhere from 1 minute to 1 hour after logging in) until only 1 was left running (that would never crash). I figured that this was an issue with Windows7's features, but it turns out that after trying it on a trial copy of Windows Server 2003 64-bit, the same issue occured.

So, I finally tried a new setup with an Operating System that YNK had ensured would work... Windows XP. I spent 120$ on a retail Windows XP Pro 64-bit (Service Pack 2) from NewEgg and installed it onto my computer. I then started up + logged into the 3-4 clients (crossing my fingers), and the clients kept crashing once again in the same random intervals (anywhere from 1 minute to 1 hour of playing).

I also heard that turning off the sound on all the clients and/or disabling my sound card may fix the issue, but it had no effect.