How are you running bitcoin normal? A shortcut? A .bat file? If either of those try double clicking directly on bitcoin.exe. If you still get the error look in the same folder where your wallet.dat file is for a file called bitcoin.conf and if it is there open it in notepad and look for a setting there.
If you don't get the error when clicking directly on bitcoin.exe check the properties of your shortcut or the contents of the .bat file. If you see some thing like C:\...\bitcoin -server remove the -server.
If you try all that and still get the error then I am out of ideas.
I don't get the error when opening bitcoin.exe, just if I double click my wallet.dat file, which I shouldn't have to do, right? So I shouldn't have to worry about this error then, I think. I was just wondering if it could pose a potential problem when I try to restore my backup of wallet.dat but it asks me for a p/w which I don't have.