my date and time always reset everytime i turn off my n810. how do i stop that. not ever turn it off? i think it started happening after i installed the lcars theme. this happen to any one else?

While you're on the topic, don't ever turn your tablet off.

There's absolutely no reason to turn the tablet off unless you need to restart it. Turning the tablet off doesn't save battery life because the process of switching it on is equivalent to several days on standby. If you need to stop it activating while it's in a bag or pocket, lock the touchscreen and keys by pressing the power button briefly and selecting that option (or on the N810 just flick the lock switch).

I've just tried my N800 with the LCARS theme and the date and time don't reset when I switch it off and on, so I don't know what the problem might be with your tablet. You're not removing the battery are you?

i was doing a hard reset, holding down the power button.

My 770 began to show this behavior after 2 years (well at least that's the time when I began to notice). It happens when being switched off for a few hours. Maybe my other tablets do the same, but I don't switch them off.
I assume the internal clock is backed by a capacitor which just runs empty after some hours. Correct me if I'm wrong.