Unidentified network in Windows 7, can't connect to the internet

[evilsatan]

I am posting this because I have experienced two very similar cases in the past week so I am not sure if it is a Windows update or not, if it is perhaps someone else here has experienced it.

Two different offices, two completely different PCs.

Office 1:
One PC would not connect to the internet over wired LAN, when set to DHCP it would obtain an incorrect IP config (169.x.x.x).
When set to static IP it would connect to the gateway but not to the internet.
WLAN card was fine and allowed a connection to the internet.
Tried different cables, different ports on the switch, connected directly to the router, nothing helped.
Cleaned registry, flushed DNS, updated NIC drivers, repaired the TCP/IP stack.
I tried a few more things but stupidly didn't make a list :/
Later that day it just started to work again, no reason for this.

Office 2:
Same as above but would not connect to the internet using wired or wireless (wireless is a PCI card so not integrated).
Tried the same steps as above, disabled the Apple Bonjour service, installed the Reliable Multicast Protocol.
Safe mode had the same problem, system restore did not help.


In both cases all other devices in the office worked fine over wired or wireless. Has anyone else seen something like this? I am visiting Office 2 in the morning so will take cables, a replacement router etc. but everything indicates the PC is at fault and the fact the wired and wireless is playing up would indicate to me that there is a software fault/corruption preventing WAN access. Either that or a power surge could have damaged the components but everything else seems to be working fine.

Cheers

EDIT:
To add, they use different security systems. Office 1 uses MBAM Pro with Eset Endpoint, Office 2 uses MSE (I just need to check it doesn't have McAfee enterprise installed but there is no reason why this would be installed). Both use iTunes so I will be trying to remove that as there was an update recently, not sure if they both installed it.