Shared wireless printer suddenly asks for password?

I have a desktop running XP up to date with all updates. I have a laptop that
has been printing to the printer attached to the desktop wirelessly.
Everything has been working fine until yesterday when I couldn't get a
document to print. I went into my printer settings and I saw that the printer
said something like 'cannot connect', so I tried it again and it suddenly is
asking for a username and password. I don't understand since I never used one
before and it printed fine. I even deleted the shared printer and tried to
re-add it, but it still is asking me for a username and password.

I also noticed that my SharedDocs with the desktop no longer connects. I am
using a wireless router to connect to the internet and it works fine. It's
the sharing stuff that seems to have gone away.

What's happening and how do I fix it?