Weird problem with keyboard

So I have this odd problem with my keyboard when I play games on windows 7 professional x64, it is kind of difficult for me to describe but I have two distinct examples:

• When I crouch in bad company 2 (holding ctrl) my character will crouch for awhile, but after a few seconds I will stand up for no reason, and I still have control held down.
• In all points bulletin reloaded I hold shift + w to run, I will hold them down, begin running, then after a few seconds I will stop (I am still holding down shift + w), and if I keep holding them down and hit another key (say a) I will begin running again.

I have tried to replicate this issue outside of games (holding shift+w in notepad, or control and another key in notepad), and I cannot replicate the problem outside of these games, so for some reason my keyboard is just being weird in games. I am using an average Logitech y-sae71 sk-2930 keyboard with this For only $2.93 each when QTY 50+ purchased - USB to PS/2 Dual PS2 Converter Adapter | USB to PS/2 Adapters
adapter.


Any ideas on how I can fix this, or what is even causing the issue?

I did some testing and here is what I have found out:
The problem only happens when I am holding down a key or a combination of keys, and then introduce a new key, here is what I mean:
if I hold ctrl to crouch in bad company 2 I can crouch for as long as I want, but if I hit another key (lets say I tap a), in 6 seconds I will stand back up even though control is held down. If I am running in APB (shift + w), and then hit a key (lets say [), in 6 seconds I will stop running. So no matter what key(s) are being held down, if I introduce a new key, the fact that the other keys are still held down seems to be forgotten. I tried 2 different ps/2 keyboards with my converter and they had the same 6 second problem. I then tried my n52te which I assume works just like a usb keyboard, and the problem did not exist. So I guess the converter is the problem, unless someone has an idea of how to fix it I suppose I will be best of by purchasing a USB keyboard.