> We don't use disk shadowing.
> We only have one hard disk.
>
> Do you have more ideas?
>
> Thanks!

Having only one disk does not negate shadowing - by default Win2003 sets
itself up to shadow disk content onto the same disk. You need to check the
disk properties to see if it's setup. If it's an upgrade from NT, shadowing
is not set by default.
Alan