Networking Issue

Crossposted from the Malware forum....

Here's a rundown of the network we share with the neighbor...

Cable --> Modem --> Neighbor's Router

Neighbor's Router goes to Neighbor's Computer and My Router

My Router connects to my 3 computers (A, B, C)

Everything was fine and dandy up until a week ago when one of my computers tried to change Neighbor's Router to run on subnet 0.0.0.0.

Neighbor's Router then kicked computers B & C out of the network, while leaving Neighbor's Computer and Computer on. Only side effect was slight slowdown on the internet.

This happened for a few days off and on, after my neighbor reset things.

Then, a few days ago, one of the computers automatically installed BearShare on Neighbor's Computer! Only Computers B & C had been running BearShare. I have since uninstalled Bearshare from B & C, but have not reconnected them to the network (neighbor doesn't trust them yet), but have not checked for anything BearShare related in their registries....

Any idea on what may have caused this?