I am seeing other computers on my network that I do not recognize

Hello fellows. I have probably a security issue:

I have total of 5 routers, three of them are wireless:

192.168.0.1 (Netgear) has WPA-PSK [TKIP] + WPA2-PSK [AES] security enabled
192.168.0.2 is wired only router (Linksys).
192.168.0.3 is a wireless router Linksys with TKIP+AES security enabled
192.168.0.4 is a wired only router (linksys)
192.168.0.6 is a wireless router Netgear with 64-bit WEP key protection.

All except 192.168.0.1 had DHCP disabled.

A set of computers are connected to these routers, with IP starting with 192.168.0.100, one embedded system on 192.168.0.5 (boiler monitoring), and one PC attached to 192.168.0.12.

Here is a list of attached devices as reported by 192.168.0.1 (with DHCP enabled):

# IP Address Device Name MAC Address
1 192.168.0.2 -- 00:1D:7E:E0:AA:52
2 192.168.0.3 -- 00:23:69:20:A0:89
3 192.168.0.4 -- 00:1C:10:8A:06:02
4 192.168.0.5 -- 00:90:C2:E2:7A:E5
5 192.168.0.6 -- 00:09:5B:72:82:82
6 192.168.0.12 COMPUTER-3700 00:08:A1:0D:74:67
7 192.168.0.102 VLAD-N68S3 00:30:67:9D:82:59
8 192.168.0.106 BASEMENT-STATIO 00:19:21:C2:BA:F2
9 192.168.0.111 VLAD 00:18E:A2:48:FF
10 192.168.0.113 PRINTER 00:09:6B:93:42:C2

I recognize all of these computers. Here is the problem:

When I go on my Win7 desktop (192.168.0.102) I see weird networks. I recognize all of them except: ATHENAS, KYLEDUITS-PC, and EXPERIEN-FCDE6E. See image: s12 . postimage . org / 4v9cx2djh / screenshot . png (remove space).

When I go to ATHENAS, I see weird files and folders with a screen shot folder of some game that I never heard of. It seems to me that some other stations are attached to my network. How can I check?

Thanks much!!!!!!!

somewhere in your routers configuration pages you will find a list of DHCP Clients, and another list of Wireless Clients. If you find funny furrin computers on those lists you will know which router is letting them on. Not a Netgear guy so I can't narrow it down from this description.