NexVision

Jake is the man posted it before I could. I also found its very good to have a OSX VM running on your windows box. Just in case.

I am running a 7240 without touch as well. I used the guide on the front page of this thread I personally like clover better then chamelion. But the choice is up to you. Anyways my system runs great no complaints at all.

Surprisingly the only time I get a crash is when trying a cold boot. Sleep works awesome sat here and raced my yoga 13 which is windows 8.1 and boots fast and wakes up even faster. If I boot with -v I dont have a issue it boots right up and reboots work fine as well. Since my work gave me the laptop I didnt get to choose the 1920x1080 screen so mine is the 1366 that could be causing a little difference. I am running the i7 with 16gb ram though. Have you tried editing the .plist and removing some .kexts from the extra directory (or rename them makes it easier if you need to fix in single user mode). Each system will have a level of uniqueness to it even with all the same hardware so trial and error is best also recommend using a external drive and running time machine right before u make any changes makes restoring a breeze.

I would say check your .plist and your Extra dir. Also try grabbing the ssdt at the bottom of the first post here. https://osxlatitude.com/index.php?/topic/6472-dell-latitude-e7240e7440-with-mavericks-1092/&do=findComment&comment=37490 I had to make changes to my .plist for my settings and install the .kext's with kext helper to get it just right. For the boot up brightness issue I removed ACPIBacklight.kext from the Extra dir. Make sure your BIOS is up to date as well. Maybe try 10.9.4 thats what I started with I am now on Yosemite and have a fully functional reliable machine thanks to this guide.