Hello, I got same problem with my desktop PC:
MB: ASROCK H61M / U3S3
Intel G620 2.60GHz
Genius USB Keyboard KB-110
Windows 7 Ultimate x64
1. Turn on PC --> keyboard works normally
NumLock LED: on
2. No activity, PC go to sleep mode.
Press keyboard or mouse button to wake up PC, NumLock LED still on
---> these characters change:
m -> 0
j -> 1
k -> 2
l -> 3
I think it likes laptop keyboard, but this is desktop not laptop.
Here I have done:
1. Turn off NumLock (LED becomes off). Yes, it will makes m, j, k, l, etc become normall again but Numerical keys on right side will not work
2. Restart PC.
3. Unplug USB keyboard then plug again.
4. Change keyboard to PS2 model.
Last one is what I did right now. It seems solved, but still curious what's the real problem.