I do not believe that you're really using DHCP, if you're all competing for 192.168.0.100. Or else the router gave you all a long-life lease on 192.168.0.100.
Here is a checkup list for verifying the settings:
I suggest on each of your machines, to go to Network Connections / Local Area Connection / Properties, uncheck IPv6, go to IPv4 / Properties and make sure to check both "Obtain an IP address automatically" and "Obtain DNS server address automatically".
Next. As I never had a Dlink router, this is from the online manual:
Login to router configuration at address 192.168.0.1, go to Network Settings and then DHCP Reservations List, and delete all entries. Or got to Number of Dynamic DHCP Clients and do Revoke to all the entries.
This is so that the router will forget that you're all 192.168.0.100.
Ensure also that under Network Settings / DHCP Server Settings you have Enable DHCP Server, and that DHCP IP Address Range is 192.168.0.2 to 192.168.0.254.
Now turn off all the computers, reboot the router, then boot all the computers.
If the situation isn't re-established correctly, reset the router to factory settings and reconfigure. If this doesn't help, then your home network is probably haunted.