I'm giving up on trying to figure this out on my own. I'm sorry for the length of the post, but I've already done a lot of troubleshooting. Here's the story and what I've done so far:
A few weeks ago, my Dell Inspiron 15R (N5110) laptop began failing to go to sleep and shut down. If I click sleep in the start menu (or suspend in Ubuntu), the screen goes black, but the power light stays solid (it's supposed to slowly flash when asleep) and the little wifi light on the front stays on (which, I think, usually would turn off when asleep). The fan will then turn on anywhere from 5 to 60 seconds later. It stays like this. There is no waking it up from this state. I have to hold the power button down for a hard reboot.
A soft shut down is similar. It goes to black screen (I think Ubuntu may stay on a splash screen for shut down) and lights stay on, etc. Never fully shuts down.
Restart seems to work properly.
Now, this did happen around the same time that I tried to update Ubuntu Studio (I was dual booting Win7 and Ubuntu Studio at the time). The update did not work. Upon rebooting back into Ubuntu, it would (and always did) go to a grub terminal rather than loading the OS. I do not know if this was related or not.
I was seeing errors in some Windows logs after a failed sleep, but googling the error codes got me nowhere. (It was just stuff like "this error code means Windows failed to properly hibernate"). I'll have to find those again if anyone thinks they'll help.
Also, I tried it with nothing plugged in (usb, monitors, etc.). I tried it plugged in to power, battery only, power no battery. All had same results.
I tried reinstalling/upgrading several drivers (video, chipset, wifi, BIOS) in Windows using the Dell website. None of it helped.
I've tried taking the battery out, unplugging everything, holding power button down for a while, and letting it sit for a day (reset CMOS?). Didn't help.
I finally totally reinstalled windows from Dell recovery (this was not from an image I captured earlier, it was a full reinstall to factory settings) and I have since installed Ubuntu 14.04 LTS over the old Ubuntu Studio. None of this helped.
So, FINALLY, I decided to replace the CMOS battery, which I had seen that someone else said it was the only thing that worked for them. Aaand...... It worked!!! After replacing the CMOS battery, I was able to put the computer to sleep in both OSes.
Now, it's been about a week, and the exact same thing is happening again. I have no idea what's going on.
Also, there were no signs that the CMOS was going bad. No errors showing up at boot. The time system time was acting normal (although, sometimes the time would be an hour earlier than it actually was. It'd been happening for like a year though, but I never figured it out. Just had to reset it in Windows once I noticed).
One more possibly relevant thing. I have a guitar pedal that I plug in via USB to interface with the computer. Sometimes, when it is plugged in and the computer sleeps, it would shut down instead of sleep (and the whole "your computer was shut down improperly" stuff upon booting back up). BUT, just like the time being an hour off sometimes, this has been happening for around a year, and I kind of assumed the time issue was related to the pedal. Not sure if this could somehow be related.
I've exhausted all my knowledge (i.e. google searches...) about this. Any ideas? I see some people say that the mother board may just have gone bad, but that seems like a cop out answer to me. I at least want something a little more specific about it being bad, since the computer is perfectly functional other than sleep and shut down.
Sorry for the length. Thank you very much for reading.
-BAM