Help! Couple rigs unable to mine

So I recently added a number of rigs to my mining farm (from 4 to 13). All of them are running Litecoin BAMT 1.3. After some minor instability issues, I managed to get them at stable clocks with low rejected rate.

However, today one of my rigs had a hard hang that required a reboot. Upon rebooting, I was no longer able to connect to any of my pools (Middlecoin for the time being) on that rig. I got the following error:

Please check the details from the list below of the servers you have input.
Most likely you have input the wrong URL, forgotten to add a port, or have not set up workers.

Shortly thereafter, a 2nd rig developed this issue. So far, none of the other ones have. When I stop/restart mining, I get a "cgminer api failed" message in the terminal. These are the things I have tried so far:

1) I have scanned my .conf file up and down and there are no errors in it: no misspellings, no missing commas, no missing quotation marks, no extra or missing spaces anywhere. I even used the search feature to make sure I wasn't skipping over anything. The pool addresses/port are correct, and since it is Middlecoin, no workers need to be setup.

2) When I try to ping Middlecoin (or anything), nothing turns up. When I try to connect to the internet on the affected rigs, I am greeted by the initial setup page from my ISP (like when you first sign up for their service). I guess it is unable to see anything outside of my network, which is strange since the affected rigs are located on the same switch that the unaffected rigs are on.

3) I have tried a fresh install on a new USB stick. Still the exact same issue. I have even tried Litecoin BAMT 1.2, 1.4, and 1.5.

4) Tried a different port on my switch, a different CAT5 cable, and even ran one directly to one of my modem's ports, completely bypassing the switch. Still nothing.

5) Thinking it might be my router's firewall, I tried disabling it. Still nothing.

6) I read somewhere to uninstall network-manager and install wicd (even seeing people report that just uninstalling network-manager fixed their problem). I tried doing this, and still had the same issue.

I am seriously stumped. Anyone experience this same issue, or have any ideas on how I can fix this? Google search didn't seem to turn up much in the way of this particular problem. I am dumbfounded that this is only affecting two rigs that are on the same network as the other 11 unaffected rigs, with the same settings. Once I had gotten all of them stable, I didn't mess with them in any way, just let them mine.

EDIT: BAMT is my first Linux OS, so I am not really well-versed in how to do things in this environment just yet. Just wanted to throw that out there, in case a complicated solution was given. Still learning my way around the command line.