Vista Home Prem.
For the last week (Wk of 1/11-1/18/2009) my computer clock intermitttently reverts to December 1899.
Have reset it several times and it will be OK for a few hours or a day, and then while I am using it, or sometimess when I start up, I will be back to 1899.
Have run anti spyware Spybot etc. and still having this problem.