How come I could connect to a computer on my local network to do Remote Desktop but now I cannot?

[Ziptagger]

I am trying to use remote desktop on my PC (192.x.x.103) The settings are configured correctly, the remote services are started, the firewall allow RD. I was using it on Friday and all was well.
Doing basic trouble shooting, I noticed I can ping my Domain controller (192.x.x.1) and other servers but no other computers on my network.
The other PC (192.x.x.133) can ping my pc and even remote into it.
They are on the same network, same subnet mask, same default router, same DC.
Also on my PC (192.x.x.103) I can ping and access the internet with no problems.
My pathping from the PC i want to remote into, to the PC I’m having issues with is:
1. 192.168.100.133
2. 192.168.100.103

[Ziptagger]

The PC’s are set to DHCP IP addresses with the DNS pointing back to the DC statically.

No routers, hardware, configurations changes that I know of have been made.
I have disabled the firewall, rebooted, cmd as an Admin and still cannot ping my other PCs.

The DC is set as DHCP and DNS roles. The services are up and running, I just checked the logs and no errors for the last week.

The network set up that I have is 2 cat5e cables coming from the wall to my station. One goes directly to a Linksys Phone then to my PC (set up for everyone else as well) The second one from the wall feeds a netgear 4 port switch, which feeds a NAS and a workbench station that I use to repair computers.

From this work bench pc (x.x.x.133), I am able to ping my desk PC(x.x.x.103), my DC (x.x.x.1), and the internet, but no other PC’s on the network. Nor can any other PC ping my workbench PC. I am able to remote into my desktop from my workbench (XP).

My Desktop PC, cannot ping my workbench PC nor any other pc on my network except for the Domain Controller. But it can be pinged by every other PC on my network.

My desktop is in a IT group with high level security settings and I’m a Domain Admin user and in the Remote User group.

[Zachary]

I think that you will need to add the private ip range to the trusted zone so they can communicate properly. Either you have the router set to block pings universally or for either machine, or the remote 136 machine has a firewall that is blocking it. After investigating those 2 possibilities, disable IPv6 in the network properties and disable IP Helper service, reboot.