Right, this problem has been driving me mad for the last few hours, so going to give you all the details.
First, network set up
All systems are running Windows XP Professional with SP2 and all updates installed with no other firewall installed except for SP2 firewall. All comps using AVG Free Edition
Last night was browsing the internet fine on my main computer and shuttle doing downloads as usual. Came back from work this afternoon and after booting up My main computer (shuttle is always on) it took a lot longer than usual to load the taskbar. Eventually it came on but the network icon was showing "Limited or no connectivity", noticed in IPConfig that no IP or DNS were set. Have tried the following things to repair the connection.
1. Tried the simple "Repair" connection, no luck
2. Put network cable into different network socket on on mobo (DFI UltraB), no joy
3. Put network cable into different port on switch, no joy
4. Replaced cable between Main comp and switch (and repeated step 2+3), no joy
5. Tried manually assigning IP and DNS, no joy
6. Checked router and DHCP table did not show main comp as being connected to network
7. Installed a PCI network card (tested on other machine and works), same problem
8. Un-installed drivers for on-board LAN, then re-installed, same problem.
9. Checked router logs, no sign of blocking my main comp
10. Disabled SP2 firewall, no joy
11. System restore to time when I know I was browsing the net, no joy.
I think I've done everything I can without re-installing WinXP (Which I don't really want to do), pretty much ruled out hardware problems as shuttle is downloading fine. Currently running a virus scan to eliminate that possibility.
Only thing I can think of is un-installing TCP/IP from the main comp, but that doesn't seem to be as simple on WinXP as on other versions of Windows (Would this work?, if so how).
Any suggestions or has someone come accross this before, I'm going nuts here.