What is your firewall?
Installing a VPN client that provides it's own virtual adapters can often break a third party software firewall. You may need to remove and reinstall you firewall.
I recently ran into an almost identical problem with Sygate Personal Firewall and the Juniper provided NetScreen Remote VPN client.
The fix was: remove both firewall and VPN client. reinstall VPN client THEN reinstall firewall.
I'm sure you checked your basics.. DNS settings etc to make sure they arent pointing awry...
Have u rebuilt your TCP IP stacks or reinstalled TCP/IP?
MXO has always worked fine for me. Today out of the blue, the launcher stopped working.When I open it, it will load to the line "Client version... xxxxx" and then stop. Doesn't even give me the option to log in.The only other time I've had this was on my brother's computer, if I tried to open MXO on a non-admin account. But I've tried the client on both my account and the root Administrator account, and nothing works. I'm stumped. It doesn't let me do a system check, and I have tried copying the launcher.ping to/from login.thematrixonline.com works fine.
try to reinstall TCP IP...
it can really make a difference..
You dont have to reinstall xp for that..