HP Laptop Freezes, But Only When Idle

[boweasel]

My wife bought a refurbished HP Pavilion dv5 laptop recently (32 bit Home Premium), and although she's happy for the most part, there is one unfortunate characteristic she'd like changed - whenever she lets it sit for at least an hour it invariably freezes. It never freezes on her while she's in the middle of using it, but if she (say) reads and responds to her email and leaves the screen on her email list for an hour or so it will be completely unresponsive upon her return. No cursor. No Ctrl/Alt/Delete. She always has to hold in the power button to reuse the PC.

I've done full Malwarebytes scans, run TDSSKiller, run ComboFix. Set up and run chkdsk /f at boot. Everything looks okay. When I check the Event Log the only thing I can ever find are errors related to the non-sanctioned shutdown. But maybe I'm not looking in the right place.

I could use some advice on what tests or applications to run.

 

[richc46]

After use, put the computer in clean boot mode.
When you return if the computer is frozen, follow clean boot prodcedure to find the cause
If it still freezes, let us know
Troubleshoot Application Conflicts by Performing a Clean Startup - Windows 7 Help Forums
For Vista too.

 

[Patonb]

See if in the bios you can turn speedstepping/cool n quiet off.

I'm wondering if it downclocks and undervolts too low.

 

[wither 3]

It sounds to me like the Power Mangement configuration is set to turn the system off after x minutes.