I recently started getting the exact error too. I contacted sbc yahoo
support and went through all sorts of test (most I had already tried). I
tried accessing my email from two separate computers I have using outlook
express and got the same error. I was convinced at that point it was the
ISP's problem. They recommended I try another mail client, which I tried
thunderbird and I then started receiving my mail. My guess is what ever the
most recent update from MS was the issue. I am still going to try and figure
this one out. I'll let you knw if I have any luck.