Originally, the Negative and Ground were combined in both of the breaker boxes.
-They are now separated.
The ground wiring in my apartment, on the outlets I am using, was barely connected.
-This was fixed, they are properly connected now.

I added a Separate ground rod for my apartment. (My apartment's breaker box / wiring comes from the breaker box / wiring in the main house.)

The electrical noise has been greatly reduced, however: it is still causing problems. For example: when I touch my mouse pad, my mouse gets disconnected briefly.

My brother in law suggested that there's noise on the Negative line, since my ground is completely separate now.

Regardless, what can I do to remedy this problem?