Can not get keyboards to work properly in Windows Vista

Recently I was playing a game on my computer with a microsoft wireless mouse/keyboard set that I have owned for about 5 years. The batteries were dying in the keyboard so i went to change them and realized the last set leaked into the keyboard. So I kept the mouse plugged in and plugged in a standard keyboard via the ps/2 port. The very next day my keyboard was doing random stuff. I could open notepad and hold a letter down and it would look like this....

jjjjjjjjjjjjjjjjjjjjjj
j

jjjjjjjjjj
j

jjjjj
jj

jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj

jjjj

It was like my keyboard had a mind of its own. My first thought was this is a virus so I did a complete scan with AVG a few times and it didnt fix anything. I also downloaded adware and did a full scan. Then I uninstalled AVG and installed Mcafee and did a full scan with it. I picked up a few bad cookies but nothing significant. After this I went in my attick and found another standard keyboard (ps/2) and plugged it in and it worked fine. Today I went to bestbuy and purchased a saitek keyboard and came home to plug in and install the drivers and all my problems started back up. The numlock will not turn on and off correctly, when i press various letters it does commands like closes the window, switches tabs, etc. I completely uninstalled all keyboard drivers from device manager and reinstalled several times. Also I noticed my mouse works fine for the most part but if i click on one icon after the next on my desktop instead of highlighting each one individually it highlights every one i click on (like i am holding cntrl down). So I unplugged my new keyboard and plugged it in on my laptop and it works great.

I am not sure what is causing this strange problem. I have a two year degree in computers and find myself pretty understanding of them. I built this particular system but this problem has me twisted. My computer specs are as follows...

Windows Vista 64 bit
E8400 3.0 Intel Core Duo
Asus nvidia 750i motherboard
4gb g skill ddr2 memory
2 seagate 500gb drives raid 0
geforce 8800gt 512

I appoligize if i have left anything out. I am extremely tired and should be sleeping now. Thank you all in advance.

Well I woke up early this morning and started my troubleshooting again and noticed that the keyboard worked in the bios and anytime before windows vista loaded. Narrowing the problem down to the OS I booted from the dvd disk and restored windows from a restore point from about a week ago. When windows booted my keyboard now works fine!!

I am not sure what has caused this problem. If it was malware it was something pretty serious considering Mcafee and AVG didnt pick it up after multiple full scans. Anyways I hope this post helps someone in the future.

Well I guess I spoke too soon. Today the computer worked great all day then I reboot it and now I have the same problem as earlier. This problem is getting the best of me.

I had the same problem with an ergonomic keyboard. I tried installing drivers and all kinds of stuff - but I ended up jsut getting rid of it - good luck on figuring it out.