I am also having a problem with random crashes with Lightroom 4 on a Windows 7 64 bit computer.  Had no problem with Lightroom 3.  Am concerned.  Hoping Adobe comes up with a solution.

Running Lr 4.0, and Lr 4.1 RC2 on Windows 7 Pro 64-bit, i7 Quad Core and 16Gb RAM. I have not had a single crash in either 4.0 or 4.1 RCxx

I have imported 3 Catalogues, to both Lr 4.0 and 4.1RC. I tested exporting the catalogues from both a couple of mins. ago, and all went fine.

Strange behaviour...not consistent (mine works, yours doesn't). My three catalogs have about 7000 images in each (Canon 5D MkII and 7D CR2's)

I am encountering same problem, ever since I have started using 4.x (now I am running 4.1 RC2), everytime I export images, Lightroom crashes the whole system. It never happened when I was using Lightoom 3.x. I am using Windows 7 Ultimate 64-bit, 8GB RAM, SSD III, ATI Radeon 5700, AMD Phenom II X6 (six-core) 2.8 GHz.

good news, bad news.....first the bad news, sorry others are having it....good news, is that this many having it might help provide the clues to fixing it.   I have a good copy of LR4.1 rc2 on my notebook , a big photo opp the next several days and plenty of import export time next week....hopefully we can collectiviely identify what is causing the problem and go forward.

Having the same problem windows 7.

I am also running the 64 bit version.

It might be interesting to remove the existing tablet driver anyway and see if it made any difference. It could always be reinstalled if it turned out to be a red herring.

I removed all my waccom drivers, and it continues to crash....actually pretty frequently...never had the problem with LR2 or LR3...happens on two machines running Windows 7...killing productivity.....

hate your are having that experience but I guess misery loves company. Unfortunately, I need to RC for processing the 5dmkiii images or go back to using the DNG converter...in any case, even if the crashes were eliminated, the processing speed is best timed with a calendar....killing my productivity....and I use the Nik filters so I prefer to come out of LR as a smart object in Photoshop.....agonzingly slow....hope they figure this out because I am way behind on processing shoots in Alaska and Minnesota....

not sure how to register....I scanned a number of the popular nature photography forums and see noted pros complaining about the slowness and their frustration....I have not posted on those forums about the problems i am seeing but may do so in hopes they have a bigger voice....With the  new 5dmkIII in hand and taken on a number of 5 day wildlife shoots already , the 1dx on order and  a 21 day safari coming up, it is very frustrating when I think of where the necessary version of Lightroom is at the moment...I admire and am a big advocate of lightroom going back to LR2, but this is killing me.....hope they discover/fix the issue soon

I always have crashes when my (USB) printers are on - so I turn them off when I am importing - no problems then.

I have Win 7 65 bit.

mine did same – I have epson printer and HP printer both usb – I unplug them when working in LR- and unplug sd cards etc. I don’t get any crashes when I don’t use usb’s.  hope your solution is that simple.

I was getting some crashes with LR 4.1RC2, sometimes taking out Win7x64 as well. I seem to have solved that by uninstalling several things. The most likely culprits were the AMD graphics card stuff. So I uninstalled the Catalyst center, Hydravision, the 3D stuff, - everything except the basic graphics driver. I also uninstalled Windows NEF codec, and Nikon's Nef codec, and the standalone Noise Ninja, so it wasn't a very good experiment. But it cured the crashes. I didn't bother trying to find out exactly which was responsible.  Graphics drivers are notoriously buggy, and the nVidia control center was noted for causing problems back in LR2 days, so I would put my money on them being responsible.

Bob Frost

I am also crashing on Win7 64bit...but not just Lightroom, it actually crashes my whole machine. I'm on a fresh install of Win7 with only CS6 & Lightroom installed. Lightroom so far has been the only program to cause this, and it typically happens when I'm adjusting filters or moving sliders for example. I'm guessing it's when I'm taxing the CPU/memory a bit...However, when performing the same type of tasks in Photoshop, AE, etc., I have not experienced any crashes. I've ran some diagnostics on my memory as well as my hard drives to hopefully rule out any hardware issues, and it all seems to check out OK. Because it's crashing the whole machine, I'm unfortunately getting no feedback in the system/error logs. I'm at a loss right now, and it seems others are only having application crashes.

System specs:

Windows 7 Pro - 64bit - Service Pack 1

Intel i7 960

6GB RAM / (2) SATA III 2TB Drives

NVIDIA GeForce GTS 450 w/ Dual Monitors

CS6 Creative Cloud

Lightroom 4.0

I too have spotted crashing in LR4 RC2 but only when I installed Apple Quicktime Pro on my computer.

LR4 RC2 will sometimes crash twice before it loads up successfully.

What version of QuickTime did you have installed?  Also have you tried LR4.1rc2?  LR41rc works much better for me than LR 4.0 release.