i have written a small program that displays the login and logout time of the user in the pc and it is working fine in some pc and giving segmentation fault in some pc and the backtrace is something like this. i am using gmtime function for time. can any tell me the exact problem.

0x00a46100 in getenv () from /lib/tls/libc.so.6
(gdb) bt
#0 0x00a46100 in getenv () from /lib/tls/libc.so.6
#1 0x00aafbcf in tzset_internal () from /lib/tls/libc.so.6
#2 0x00ab07a8 in __tz_convert () from /lib/tls/libc.so.6
#3 0x00aaeba1 in gmtime () from /lib/tls/libc.so.6
#4 0x08048a43 in LoginUserInfo ()
#5 0x080490a8 in main ()
(gdb)