Please explain your situation as clear as possible, what problem are you facing? Does it gives any error? Don't know what the error is then post any screen-shot if any.
Did you tried on another PC? What did you tried to rectify the issue?

You can head to link below for official FAQ troubleshooting

Gonna do a bit of hunting this coming Saturday, G502 or G402, going to replace my now not-so-healthy any more MX518 first gen, been smashing the switch hard recently due to FPS heavy and... I already repaired that switch several times and now I think the zink already worn out beyond limit, it's time to retire him and give him a good RIP... since 2003, the good-old-day.
Anyone know any shop at this poor Kuching, Sarawak here selling the latest Logitech G series? Last few months I can still see the obsolete G400 (non-S) and even the G500 (wow.. ).

RM50 for a mice? DHL + Insurance?
May go to the PC Image at tHe Spring, been long didn't step in there.. hahaha...

Already been using for about 2 weeks+.
Please head here for my first impression, I've yet to do any long gaming session to give a another impression on this mice though.
Btw it's G502, one great jump from MX518 (obviously).

This post has been edited by wildwestgoh: Sep 6 2014, 10:18 PM

The shape, how do I describe then?
It's more resemblance of Razer Deathadder? Some sort of that shape, instead of the old higher back and lower front of which the MX518 till G500 does.
G502 seems to move out from Logitech traditional design, feels much comfortable I guess, I can claw grip, palm grip without any issue.
But if you look at my impression, I wasn't using it long enough yet to detect ache of my wrist so... comfortable wise still rank high.

It depends on the size of your hand and your claw grip style, if you only compare those 2, I would definitely say G502, G602 is more for MMO?
Then again the G602 sort of resemblance the G402, slightly lower at the front, kinda making claw grip a bit tiring on the long run? (IMO )

Same goes to G502, the sniper button or known as lowest DPI switch is located just below the left click, some people with larger hand may feel the button is too easily prone to accidental click. But it is just right for me, probably my hand is smaller, MX518 feels a little longer but still comfortable enough.

New technology term used by Logitech for the new generation of mice's sensor tracking, it's confirmed by several source (lazy to post) that it uses G100's sensor + accelerometer and gyroscope combined to compensate the speed limit of the stock sensor.

Unlike G502 which utilize the full Pixart PMW 3366 sensor, G402 has extra sensor for even higher speed tracking, accuracy wise has not been confirmed yet, but so far it has pretty good review.

p/s: OK, here's one source that state it... it's a review btw.
http://www.pcper.com/reviews/General-Tech/...e-Accelerometer