Checked a lot of forumer also facing this kind of issue..... still no cure.
What can we do ? 

Well for me I can live with it. Now at 10PM and I still have another 1hr 22min to go (+-35%). Seems that the battery is not giving an accurate reading to windows. The 1 hour reading has been there since 1 hour ago...  , by right I should have 30min or so left.

Other notebook also has their own specific problem. Been using Latitude for almost two years till now (company asset), there is one buzzing sound near the notebook ac adapter socket since day one either plugged in or not. All other Latitude in my company has this unpleasant sound.

My ex-Satellite (now with my brother) has optical drive problem just one week after the warranty period. It started to be picky on the media. Funny part is, I seldom use the drive. Only using it during the installation of applications and that was after recovery process.

My company is Dell hardcore fan. Their built quality, I would say different across models. We have all the Dell models except Alienware n Adamo. Latitude is a good notebook but XPS was top of the list for being the worst. Imagine 10 units of our XPS have changed almost every parts from mobo, hard disk, battery, LCD, memory.... all less than a year under moderate usage (only senior management using this model). Their support response is the only reason we stick with em.

Wifey company using HP. The ex unit which is NX6XXX series and the newer unit Elitebook has this same problem. It took nearly 7 - 10 minutes to wake up from 4GB hibernation and the bluetooth stack was not so great.

Hope our problem will be remedied by the next BIOS / drivers update.