WarCraft 1.04b patch - No CD + Bnet.

[Krassus]

According to a message I saw on the official battle.net forums, the 1.04b patch is only to be installed for people that were getting "wrong disc inserted" (or something like it) msgs with the latest patch and certain cd-roms. They recommend not using if you had not problems, and say 1.04a and 1.04b are the same except for that change.

I would recommend reinstalling and just patch to 1.04a only. You said it worked before so it should work again. Ignore the 1.04b patch.