System feezes when try to download

Having had the system freeze a number of times when I tried to download files in IE8 and Firefox I decided to try Chrome, so downloaded it and also afew extensions.
Went to a particulard (legal) website to download a PDF file and as soon as I clicked the down arrow key the system just froze solid. No lights on the keyboard no matter what I pressed and no red light emitting from my mouse. The Hard drive light was on, all I could do was hit reset.
Have tried to work out what the Event monitor is saying but its as clear as Mud.

Regards Cliff

Cliffl said:

Having had the system freeze a number of times when I tried to download files in IE8 and Firefox I decided to try Chrome, so downloaded it and also afew extensions.
Went to a particulard (legal) website to download a PDF file and as soon as I clicked the down arrow key the system just froze solid. No lights on the keyboard no matter what I pressed and no red light emitting from my mouse. The Hard drive light was on, all I could do was hit reset.
Have tried to work out what the Event monitor is saying but its as clear as Mud.

Regards Cliff

This can be malware related
Run a scan of malwarebytes:Malwarebytes Anti-Malware - Reviews and free Malwarebytes Anti-Malware downloads at Download.com

I use Vipre antivirus suite from Sunbelt Software which includes everything.
Its the 64 bit version of 7 premium. The PC is connected directly to my Netgear router.

Vipre is not a free Antivirus program its bought and paid for. I have been using Vipre for quite a while and do not suspect it at all. (Its from the USA)
Also it is not a BSOD the system just freezes everything is on the screen.
I am slowly deleting any programs that I can do without.
As a clue it happened one day and I started to first remove anything plugged in.
i remove my 160Gb USB drive and behold the system came back to life and I thought that I had cracked it. But the following day it happened again.
I notice now that it has not happened for a couple of days so every so often I go into each browser and try and duplicate the actions I used.

Tuesday morning, downloaded a free cleanup program (already have ccleaner & registered version of winpatrol)
but will try anything once. Advanced System Care 3 is the name so ran it and cleaned up a few things, ran the optimiser and there is an internet speed booster which checks the obvious settings. But first it redirects you to SPEEDTEST.NET to do a speed test. As soon as the site opened in Chrome my whole system froze and aprt from what was already on the screen there were 3 mouse pointers remaining.
i left the system alone for about 20 minutes just to see if anything would happen but to no avail.
Had to reboot. So guess am not so lucky as I was beginning to feel.
I have been in computers for a long time and not seen anything quite like this one before. Am trying to find a clue. Have already done all the requisite memory test which show up fine.
have defragged, cleaned, wiped, polished, but so far the beast has got the better of me.

Regards Cliff