[I keep getting a message that my clock isn't set properly.]

My time setting is as it should be, i have gone in and double checked it.. I crashed bad on site and when i went to log back in i started getting this error message. " the certificate returned by the grid appears to be expired " which does not help me 1 bit, as i said my clock settings are correct. Any bright ideas Linden labs?

[Error: Unable to log into simulator]

i have been on sl for 4 years and never had this problem until today, none of my accounbts will work,, uggggg!!!