Vista - networking problem...PLEASE HELP!

please help! i've got two computers running off a LAN network at my business (i think that's what it's called when it's not wireless). the main computer is working fine, connecting to the internet, network, etc. the secondary computer WAS working fine until yesterday morning. nothing has changed, no one has touched anything or made any adjustments or anything at all.

now it appears to connect to the network since it's still running our POS program with no problem, but it says it's connecting to "unidentified network". it also won't connect to the internet. we've tried all the standard troubleshooting ideas (disconnecting, reconnecting, restarting, blah blah blah) NOTHING WORKS!

i've read other threads & tried what other people are trying & it's still doing the same exact thing. the thing that's different from everyone elses problems is that most other people are having problems with new systems or updated systems... this computer has had no changes made to it & was working fine until now.

i obviously don't know that much about this stuff so if anyone has any ideas they would be greatly appreciated!!

Whenever the network (LAN) Local area network is in question you first want to look at the IP Address. Start -> Run type CMD. This brings up the black screen with a dos prompt. Type Ipconfig /all This will give you the Host name = computer name, and IP Address. 192.168.*.* The first 3 numbers are the network address the last one is the pc address. If it is 169.254*.* then you have a DHCP problem and you lease has expired. The resulting address is a default when there is no place (router) to get the correct address. If you are on 169.254.*.* and the other PC is correct with 192.168... you will never connect to it because of the networks are different.
If all of that is correct do a system restore back to before the last update

ok, so i checked that & just like you said, the one that is not working is coming up with 169.254. what do i do now? how do i make it the same as the other computer that is working fine?

there is 2 ways to get it working again, first is to request a new ip from the network device, to do this, type in the search bar on the start menu, "command prompt" and right click the file that comes up and run as administrator, you will see a black box with text, type in there, "ipconfig /release" then once it has been released, type "ipconfig /renew" this should request a new ip from the network device and the problem should be resolved, type "exit".

if the problem still exists, then you need to physically unplug the router from the wall and wait 5 seconds, this is a soft reset that just clears the cache regarding mac addresses and ip's stored on it, plug it back in and new ips for all.

Re setting the router might fix it but the best way is to put in a static address so in the future this problem will never happen again. Go to Run and type control netconnections this will bring up your network adapter. right click on the locat area connection. left click on properties. find tcp/ip 4 and click on it. This is where you put in a static address. Go to the working computer and get the ip address. it will be like 192.168.1.100 / 255.255.255.0 GW=192.168.1.1 or .254 dns ?.?.?.?
you will want to put the exact same numbers on the problem pc EXCEPT use 192.168.1.120 for the primary ip
Thats it. Now you will always have the correct info when the DHCP fails.