I mentioned this in the other "lock-up" thread- mine has done this once, also with the 20mm Panasonic. To fix in my case I just had to power off (not that it mattered, was stuck in locked up mode), detach the lens and then immediately reattach it. Powered up perfectly fine after that. This has happened only the one time to me, if it happens again I'll report if I have to do anything different to fix it.

I've called in repeatedly to Olympus tech support, and just this last time did the guy suggest resetting camera to factory defaults. Problems are still happening, and no one at tech support ever asked me about the firmware. I didn't even know about the update to the firmware until reading it on dpreview. The camera ships with 1.0 and 1.1 is out. Now why in the world wouldn't that be one of the first things tech support would suggest??????? I've yet to do the update to the firmware... really don't want to mess that up, and I am hoping beyond hope that that fixes the lock up problems

I experienced once, with Olympus 45mm. The screen froze, the power switch didn't turn off the display, had to take out the battery to recover.
Camera firmware is 1.1.
The only thing I remember, prior the incident I was tilting the lcd and putting it back to position. I think I pushed it too hard and maybe the shock affected the IBIS mechanism.
Touch wood, it only happened once so far.

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5DMK2 + 40D + EM-5 + GF2

This is my first experience with a new to market camera, and I will never put myself through this again. It has been a horrible experience. Doesn't matter which lens is on the camera, it locks up when turned on in the vertical position every time. That is the one way I can purposely recreate the lock up problem. I've set it to sleep after 5 minutes...there doesn't seem to be any way to turn the sleep function off completely. Also, I've updated the firmware to 1.1, but I can still get it to lock up if held vertically when turned on. I will have to remind myself that if the camera goes to sleep and I need to hold it vertically, wake it up horizontally first. Hopefully, that will work so that I can continue to use the camera... really don't want to go back to my e-410. Right now, I totally regret this purchase. I've spent so much money too.

I just tried it, turn on the unit on 'portrait' position after 5 minutes sleep/auto off. Looks like it was an isolated case.
The attached lens was Panasonic 14mm.

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5DMK2 + 40D + EM-5 + GF2

Well, it's new.. this should be covered under warranty. It'll suck not having the camera for a bit, but at least you're not out a grand.

charge the battery.

I don't know how quality control happen in Olympus factory this day and why so many OM-D user experience the lock-up. But before share your nightmare experience, it might be useful if you check everything in your camera body and lens first.

The latest OM-D firmware is 1.1, if you experience lock-up/freeze and your firmware is 1.0, please upgrade it to 1.1. Use the latest firmware utility version from Olympus. During updating please make sure your battery is full and be patient until the LCD in camera showing complete/finish. If you disconnected the cable before the updating complete your camera may brick.

You also need to check the firmware version of your lens. If your lens is made by Panasonic go to their website and download the latest firmware there.
Download | Digital Camera | Digital AV | Consumer Products | Support | Panasonic Global

If your lens is made by Olympus go to their website and download the latest firmware there.
Joint update service for OLYMPUS E-SYSTEM - OLYMPUS Digital Camera

It's also worth to look on camera, lens and battery grip electronic contact if there's dirt, or any residue that block or interference or any bend or abnormalities in pin and contact. Clean it if necessary but don't use any liquid material.

Also pay attention to the battery condition make sure you have enough juice and there's no abnormalities in battery condition. Remember there's no warranty for accessories, so material and workmanship defect could occur.

Try any possible configuration until you sure the culprit. If anything else failed share your experience here and write down the exact configuration and condition i.e camera and lens firmware, lens used, battery condition, original or 3rd party and the condition when lock-up/freeze happen.

Contact and demand the exchange or repair from Olympus if problem keep occurring.

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My Gear : EM-5, E-1, EPL-1, + Lumix 20, 14; Fujinon 55; OM 35, 135; mZD 45, 12-50, 14-42, 40-150R; ZD 35, 14-54 mkI, 40-150 mkI

Considering the camera is not even two months old, how much build up could it possibly have? I am going to the camera store of purchase tomorrow. I know eventually this will be taken care of since not only is the camera still under warranty, but I also purchased a three year third party coverage for the camera and kit lens. My frustration and extreme sadness is because I use my camera every day and love it so much. The e-m5 is like a mazarati compared to my e-410 which is like a chevette.

I keep my 3 batteries topped off always and have only used oly m43 lenses at this point. I did do the update to the camera firmware from 1.0 to 1.1 and problem still occurs. I thought I read somewhere that there was also an update for the 12-50mm lens, but it didn't show during the firmware update process.

My reasoning in posting (and I did a lot of searching first to find answers), was to hopefully find out if anyone else was experiencing this same problem and had a magic solution so that I didn't have to be without this camera even for a day.

I treat my equipment with the utmost care; I want it to last as long as possible and hope to use it in a professional capacity. I've got my very first two jobs scheduled in two weeks (a baby shower and commercial space shoot).

Just posted a few photos in my gallery to show that I am not a casual user of this camera. All the posted images were captured with my e-m5. To put it in perspective, I've had the camera since April 20 and saved 1454 photos thus far in lightroom.