Is your system losing time whilst running, or only
after it has been powered off?
If it is after a power-off, your CMOS battery needs
replacing.
If it is losing time whilst powered up, then there is
some software, most likely a heavy-duty bloated
antivirus (Norton), or something similar interfering
with the system clock. Synchronising works, but
if the problem is evident whilst powered on, it needs
to be looked into in more depth, to cure the problem
rather than keep sticking a band-aid on it.
