Greetings,
1.The computer powers on automatically after shutdown (This doesn't occur every time)
This is often cause by WoL or Power on by PCIe device being enabled in BIOS
2.If I leave my computer to go into sleep mode, it usually crashes (or turns on as if it was shutdown) when I power it up again.
Can be caused by hardware / driver combination. Piece of hardware in your kit that doesn't support low power state. Faulty RAM, Aggressive BIOS settings, over clocking. Older / incompatible FW on your boot drive or SSD, or abnormal power fluctuations in your home are all possible examples.
3.I put my computer into sleep mode manually today, after turning it back on I found my Chrome had completely crashed and didn't work again until I rebooted the computer. My other applications including Visual Studio were working fine.
The webpage you were visiting might be session based and timed out, didn't properly refresh, resume or reconnect. However, is more likely related to a hardware or driver issue as mentioned above.
4.On the odd occasion my playback device has automatically changed from Speakers to my monitor (2757-C) in the middle of listening to music.
This might be explained if you are using an HDMI monitor. The playback device should not change midstream during playback. That Kingston device you have plugged into the rear is probably being incorrectly detected by the port sense feature in the realtek software... or you have the default playback device set incorrectly in the sound card drivers or windows Sound in the control panel applet
Since the majority of your problems appear to be with sleep and resume from low power state, I would remove as many devices from the machine as possible, update all of my device drivers and test to see if I could identify what device and or driver combination is keeping the system from resuming from low power state. I would also use BIOS defaults, changing only what is absolutely necessary for the system to run. Also test my memory with memtest and try another PSU.
