The negative building times means everything takes only 1 turn to build, even Wonders of the World. This bug may have something to do with the Construction Yards in my cities (which halve building times). Earlier save games can be provided if needed.
http://dl.dropbox.com/u/8710134/Negative%20Building%20Times%20%28Actually%2C%201%20Turn%20Each%29.EleSav
Best regards,
Steven.