Heuristics scan causes my computer to shut down

[Apsara2010]

I last did a scan about a month ago and everything seemed fine. Today, though, I installed the latest version of Anti-Malware Free (2.0.4.1028) and installed the latest version of the updates - v2014.12.09.05. I started a scan and left my computer alone. About 40 minutes in I noticed the computer was restarting. I thought it was weird, but continued with the re-start process (I figured the scan had completed and automatically restarted my computer). But just in case, I did another scan and the same thing happened again, only this time, I saw the notice about "Windows has recovered from an unexpected shutdown"; I opened the error report thing but it doesn't mean anything at all to me. I started the scan again and watched it (the most interesting 40 minutes of my life!). Everything was ok, until the scan was part-way through the last bit, the heuristics scan, and that's when, without warning, the computer just shut down and restarted.

 

My computer is an HP6735s, running Windows Vista (no idea which bit or whatever). I have AVG anti-virus installed, as well as Malwarebytes. I recently installed (a legitimate) version of Office 2010 and that caused problems - my computer jammed while trying to install 42 updates (a nice person on the MS forum, thankfully, helped me sort that issue).

 

My computer is a bit slow, but that may be because it's old and getting quite full, and it done some weird things recently, like un-attach windows without me knowingly doing anything (if I'd opened an internet link in a new window, for example), although that may be down to me being tired and/or not controlling the mouse properly. 

 

Does anyone have any thoughts, please? However, I'm afraid I am one of those people who is so tech savvy they need someone to spell things out in words of one syllable - "See that little button at the top with the vertical dash in a little circle? See it? Yes? Well that's the thing you have to press to turn the computer on..." that kind of thing. But if anyone is brave enough to try to help, that would be so great. Thanks!

[daledoc1]

Hello and :

 

One possible cause for this behavior can be malware infection.

It's a good idea to exclude that as a possibility.

We cannot perform the diagnostics and removal/repair for this in this particular area of the forum.

 

So, for expert assistance, I suggest that you please follow the advice in this pinned topic: Available Assistance For Possibly Infected Computers.
It explains the options for free, expert help >>AND<< the preliminary steps to expedite the process.
A malware analyst will assist you with looking into your issue.

Thanks,

[Apsara2010]

Hello, daledoc1,

 

Thanks for the advice - I'll give it a whirl.

 

Sorry for the delay in replying - I've been using someone else's computer until I felt brave enough to tackle whatever issue there is on mine, which, I hope is now!

 

Thanks again,

Apsara2010