Win 7 freezing randomly without errors

[imaddicted2u]

My HP DV5 laptop with up to date 64 bit Win 7 OS and drivers has started freezing s few times a day.
I have to hold the power button to shut it down and it reboots successfully.
There is no error displayed, the cursor just freezes and the OS stops responding.
There is no record in event viewer.
Running sfc /scannow finds no system file errors.
Updated Java, uninstalled Flash.
Used Seatools to check the hard drive, it passed.
Ran in safe mode with networking for a while, it froze.
Malware and virus scans come back clean.
Any thoughts on what other things I can do or check?

 

[imaddicted2u]

I ran HWMonitor to watch temperatures and waited for freeze:
Temps at time of last freeze were Motherboard 150F, core1 150F, core2 150F, HDD 107F
Idle temps are Motherboard 122F, core1 117F, core2 117F, HDD 105F

 

[sumandeb6888]

1.insert windows 7 dvd repair your os
2.run memory cleaning tool
3.defreagment and optimise



if above those not worked post back

 

[imaddicted2u]

I booted from Win 7 DVD, I ran start-up repair, It said it could not repair the OS automatically. I selected restore to a previous time. Half way through it froze. After rebooting from hard disk I got an error message saying restore was not complete, files were unchanged.
I was running Smart Ram and Smart Defrag, part of Advanced System care. When my problem started I uninstalled them. I ran Windows defrag, it shows 0% fragmentation after a refresh.
What memory cleaning tool did you mean?
Windows memory diagnostic completed with no errors but upon restart the machine froze. Held power button until it shut, then it restarted successfully.

 

[imaddicted2u]

I ran chkdsk 3 times.
The computer froze at 17%, the beginning of stage 4 of 5, verifying file data, every time.
I ran Seatools from dos. It passed the drive on the short and long tests.