Work stations loose connectivity to the server

Is this after an idle period? If so check the network adapters on any of the problematic systems. By default Windows enables power management which doesn't always work as well as it should. Some time the network adapters don't "wake-up". It's not an option on all NIC, but it is on most. It's located by going to:
device manager | network adapter properties | power management tab | un-check "allow the computer to turn of this device to save power"

I have done that to the nic settings.
Internet would work one minute and not the next.
 Need to check if it happens to all the workstations at the same time

Or, does it happpen consistently after x amount of time passes.....

it happens to all the workstations at the same time
the amount of time is random. sometimes it will stay up for a few seconds, other times it stays up for several minutes or longer.

Probably not the power management issue if it is happening during short periods of time. I would still make sure the power managemnt is off, on the server, if an option.
When they loose connection to the Internet, it sounds like they may just be loosing access to the server and DNS. Next time the connection is lost see if you can ping an Internet IP or connect to a site such as Google by IP:
http://64.233.187.99/
If so this would indicate a problem with or a bad network adapter on the server, or a faulty switch port .

What are the DNS settings on your workstations?  i.e., do they ONLY list the DC, or do they also (or only) list the ISP's DNS server?

the workstations only list the DC as the DNS server.
when the problem occurs i loose connectivity to the server, I can however ping the firewall
I will try the google ip and report back.

I don't think is the ports because the workstations were using them prior to bringing the server on board

Interesting.  What you're describing could be a NIC driver issue on your server; it sounds like the something in the network subsystem is either going to sleep or blowing up.  The fact that you can restore connectivity by pinging the workstations from the server suggests that either the "ping" command is "awakening" the device, or its causing the system to recognize that some piece isn't responding, and restarting it.  If it was the latter, I'd assume you'd see some entries in the Logs occuring at the same time as your ping.  I would also expect that the first "ping" response would be much higher, while the subsequent ones would be at a more reasonable range.

A third possibility is that your switch is having issues, but the problem seems too sever-centric for that.  However, you could try swapping some of the cables around to see if the problem is related to the specific port.

i can connect to google's ip just fine.
how can i check the nics on the sever when i look at them it says that the device is functioning properly.

I'm pretty sure I already check the power management disabled.
I 'm not at the site now and don't remember if the cards are teamed or not.if they are not I'll disabel one and see what happens and then the other. If they are teamed i shouldn't have this problem correct?

>>"teamed i shouldn't have this problem correct?"
One would think not, unless it is a driver issue. That would affect both, assuming they are identical cards.

I thought I had completed this in the morning.
The problem was one of the network cards.
I want to express my sincere  gratitude  to all of you who helped on this issue.  

what else do I need to do to close this question. I accepted the solution this morning

Excellent. Glad to hear you were able to resolve.
To close the question see the following links. You need to accept a solution. You can select all those that you felt assisted and split the points as you see fit. You also need to assign a grade. The second link includes grading options.
Thanks for the update.
Cheers!
--Rob
https://www.experts-exchange.com/help.jsp#hi68
https://www.experts-exchange.com/help.jsp#hi73

Thanks josemgomez.
--Rob