Where is your server?
What integration do you use?
Thats why we have GMT setting for people with vbulletin. You keep that at 0 unless you have vbulletin at which case you set GMT to whatever you like to take GMT back to 0. Every other piece of software in the world does time correction offsets from the server.
VB does it all from GMT. Therefore if your classifieds etc posted where the timezone is an hour ahead which means your server may be in germany holland etc then you place -1 in GMT and then users like in
vb set there time offset counting down from GMT not the server.
Now if your not integrated with
vb then you simply set GMT to 0 and then set your timezone offset to -1 in your classifieds profile.