Timestamp problemer, efter flytning fra apache til iss

linje 115: while($temp=mysql_fetch_assoc($query)){
       
linje 116: $time = date("H:i", ($temp['ts_out'] - $temp['ts_in'])-3600);


fejlmelding:
Warning: date(): Windows does not support dates prior to midnight (00:00:00),
January 1, 1970 in
D:\inetpub\vhosts\idun.ots.dk\subdomains\timestamp\httpdocs\edit.php on line 116


NOgle som kan se fejlen?