Laptop keeps shutting down and immediately restarting

[Bluntduffman]

My laptop specs are
Asus U56E
Intel core i5-2410 CPU @ 2.30GHz
6 GB Ram
64-bit operating system; x64-based processor
Windows 10 Home

My laptop for the last couple weeks has been shutting down quite consistently. It shuts down and starts up immediately 99% of the time and seems to last anywhere from 20 minutes to 40 minutes max before doing so. It seems like I'm using far to much disc space according to the Task Manager. Usually due to my BullGuard Anti Virus updating, or Service Host Local Service (Network Restricted), or currently the System file is the one running very high.
I can't really stream or use Google due to this, as even now it is red lining my disc space just being on, and it doesn't appear to really be using that many MB/s in task manager, but still maxing out my disk column.
Any ideas as to why it may have started doing this just recently?
Also, now that's it's been on for 5 minutes, and no browser open, CPU and Disk are back at 0% or 1%. Not sure what to do really.
Thanks for any help in advance

 

[ffg7]

the reason for asking if have another computer was to attach this drive to that computer to run virus & malware scans on this drive.

 

[Bluntduffman]

Ya it crashed again on me. So not really fixed. My PC hasn't been used in a year and hasn't been connected to the Internet in that time. So I may need to get a wireless card for it and update it before I do that. But I will check online to see how I can use another PC to attach the drive to and do a scan or whatever.
It's better than it was, start up is quicker and only peaks for 30 seconds or so, but I missed what spiked to shut it down this time.
This may take more effort and time to correct thays for sure

 

[ffg7]

check on your other pc to see if has same data & power cables that plug into your sick drive. I do that all the time if I don't use my external sata drive adapter.