[SOLVED] Internet/Network doesn't accept new PC's?

[Pedro Senedesi]

Hey guys, I've run into a problem on my work today.

There's a PC there that keeps turning off. So I got another old PC that works OK to replace that one. Fresh install of Windows 7.

But there's a problem. My network doesn't seem to accept new PC's. Everytime I get a PC that's from somewhere else, being a fresh install or not, the internet simply doesn't work. It says that it is connected to a network, but there's no internet connection. I can even go into the default gateway of my router from the PC.
The cable that's plugged into it was connected on a modern PC, that already had problems connecting to the internet, same symptoms, but I had a technician go and fix it.
I didn't want to get the same technician to fix the same problem on a diffent PC, I want to try to maybe fix it myself with the help of you guys.
I don't know if it's a IP issue or something like that... There's a BUNCH of cables over there, the guy who installed the routers couldn't have done a worse job.
It goes like this:
Modem from ISP -> Router -> Switch -> Router.
I didn't try to connect it directly to the modem because when my ''modern'' PC was acting up, that didn't fix it.
I don't know if a router, or a switch, simply doesn't allow a ''range'' of IPs to be connected, I don't even know if there is a limitation like that.
All I know is that when my PC was doing the same thing, the guy who I called was able to get it fixed... my guess is that he changed something in Windows settings, or something like that.
I've tried to change the ''DNS'' and some other stuff on ''regedit'' but it didn't work. After a few hours of troubleshooting with no luck, I decided to try it on my home internet, and it worked flawlessly as it should, only connected the cable on the back of it and it worked perfecly.
Anybody knows any setting, ip, or whatever that might make it work?
Tomorrow I'm going to work in the morning and I wanted to get it to work by lunch, because the PC that keeps turning off is causing a lot of problems.
Sorry if I made any mistaked writing this, english isn't my native language.

Thanks guys.

 

[SamirD]

Sounds like the technician you've hired in the past has configured the network in such a way that only he can set it up to hand out IP addresses, but this is just a guess because that network is a mess.

You have to decide if you want to learn enough to simply redo your entire network so everything will work properly and you will have enough knowledge about your network to never need that technician again; or if you want to just pay this technician again to get this system online and get back to work.

As far as the system that's shutting off--check the cpu cooler and power supply.

 

[gggplaya]

Maybe the technician set the DHCP lease time to unlimited in the router or the DHCP range is too small in the router.