Black screen when put to sleep, not responding

Hello

Sometimes (NOT ALWAYS) my laptop simply doesn't respond when I put it to sleep mode. I just click put to sleep, then it is behaving like it is going to sleep, but then it "freezes" on black screen, HDD is running, fan is running, led indicator is flashing, but it doesnt respond. The only solution is to turn it off by holding power button for several seconds. I thought that it was problem of my previous Windows (W7U SP1 64bit), but now I'm using W8.1Pro 64bit for 2 weeks and today, it happened again ! my BIOS is up to date, and drivers too (as I made full instalation by myself, not just some sort of upgrade). I also have disabled "hybrid sleep". and I also unchecked "allow computer to turn off this device" and "... to wake up computer by this device" on everything like USB devices and network adapters., but no change. Any suggestions ?

I have a suspicion that it has something to do with wi-fi, as it didn't happen when I was connected just with ethernet cable for 2 weeks, but it happened today as I started to use wireless connection (home network) as I came back home.

Lenovo ThinkPad Edge E531

hello, not sleeping is always a tough topic with win8 ,but it seems to me that you answered your own question.wifi causing it ,why not sure ,it coulc be driver issue ,check that you have the driver reccomended for the wifi in win8.1

Yeah maybe I answered it, but I didn't find solution. I'm using the latest drivers available for my model from manufacturer's site and for proper windows version, but I had this problem also on W7, which is odd. But if it is a problem of driver, then there isn't any solution I guess. The only chance is, that it is only some problem in settings/configuration which can be solved, but I have no idea how, I tried everything possible what I found on the internet, but still no change. I'm starting to be desperate, because this is a huge problem for me, as it just randomly freezes when you put it to sleep, so you lost everything what was opened in that time, and also hard drive probably suffers from frequent restarts.

wifi module is Broadcom BCM43142, do you think that somewhere exists newer drivers (not that ones from Lenovo), better said, should I try wifi drivers from different manufacturer ? I'm not sure if there could be compatibility issues or not.

Is that "Driver updater" safe and reliable ? Because honestly, I don't trust in this kind of software, they are mostly just unusable junk.