I've rebooted the system several times, and I occasionally get this message box directly after rebooting
"Unable to create file:
Registry backup will continue, but no restore information for the ERDNT program will be saved. This means that later restoration of the registry can only be done manually, by using another OS to copy back the files."
Then the computer seems to run fine as long as I don't plug in the ethernet cable. But sometimes if I plug in the ethernet cable and open firefox, it hard freezes almost immediately.
C:\Windows\ERDNT <-- This message is caused by ERUNT wanting to make a registry backup but ERUNT may be damaged, open it up and disable any automatic backups, really dont need it now.
As far as FF freezing when you plug in your lan cable, not sure, have you turned the computer off, then plug in your cable and restart yourcomputer and see if that helps.
In your original post you stated that things ran fine in Safemode but a lot of things where unresponsive in normal windows, you may want to think about doing a System Repair and maybe even a format of your hard drive and a fresh clean install of windows, if you want to do this let me know and I can link you to a windows forum that we work closely with that can help you. Do you have your windows CD or the Recovery CD that came with your computer ?