I get this problem a lot too. I must have installed and reinstalled like over 30x now. The ps/2 mouse/keyboard sometimes will just freeze or not be activated for some odd reason. It happens randomly and I can't figure out why. I've tried different configurations such as APIC, Stock ACPI, x86 ACPI, all the same. Sometime it will work and others it won't... sometimes i have to hit my power button on my desktop in order for the mouse to move and to get my keyboard working. Looks like its putting the system to sleep or suspend mode or something.

I am using iATKOS 5i with eMachine T5048. Ps2 mouse/keyboard because usb keyboard will not work at all. I get no power when i plug either one in. I know my USB ports work because when i plug in the speakers that came with my emachine the led lights up. So not sure what the deal there is.