Monitor...I hate you!

[Luca Marcante]

Hi all,
this is the problem...this is one of my problems :)

I've got the monitor divided in two parts by a vertical line of
approximately 1/2 inch.
In the left, there is the part that should be on the right (the clock of
the gnome bottom bar and what's near it), in the rigth, there is the part
that should be on the left (the gnome application menu', ecc.).

The mouse cursor, can't pass through the line, if i want to go on the
left part, i have to go beyond the rigth edge of the screen...so the
cursor appears on the left.
If i want to go on the rigth part, i have to go beyond the left edge of
the screen.

What's wrong ? Maybe an orizontal offset ? Boh...
How can i do ?
please help me...i'm going mad :)
Thanks in advance
Luca.