No BSOD and no dump but random Windows freeze

It seems that there are no dump files.

   Tip

Configure dumps

First, we want to make sure the computer is saving your dump files. Go to Control Panel -> System -> Advanced System Settings -> Startup and Recovery [Settings] Make sure that "Write Debugging Information" is set to Small Memory Dump (256kb) if it is not already.

Dump Files - Configure Windows to Create on BSOD

Next, make sure that the folder C:\Windows\Minidump exists. If not, create it (allow permission if asked). Make sure any dumps you want to analyze, whether yours or others', are in this folder. You can ZIP/RAR the files and send them to someone else to analyze as well.

A few recommendations:

Security App

Code:

Start Menu\Programs\avast! Free Antivirus	Public:Start Menu\Programs\avast! Free Antivirus	Public
Start Menu\Programs\PC Tools Firewall Plus	Public:Start Menu\Programs\PC Tools Firewall Plus	Public

Running two security application is never a good idea. Please remove Avast and Pc tools and replace with Microsoft Security Essentials: Uninstallers (removal tools) for common antivirus software

Microsoft Security Essentials and Malwarebytes, both recommended from a strict BSOD perspective. Microsoft Security Essentials, Free antivirus for windows and Malwarebytes Anti-Malware Free

   Information

DO NOT start the free trial of MalwareBytes. Deselect the option when prompted.

   Tip

Make full scans with both separately.

Start up
Keep less stuff at the start-up. Only anti-virus, this helps avoid driver conflicts and improves time to log in to windows.

Troubleshoot a Problem by Performing a Clean Startup in Windows 7 or Vista
How to Change, Add, or Remove Startup Programs in Windows 7

Basic checks: Please run these tests and report back the results

1. SFC /scannow to check windows for corruption - SFC /SCANNOW Command - System File Checker
2. Disk check for errors on the hard drive - How to Run Disk Check in Windows 7
3. Troubleshoot applications by a clean boot - Troubleshoot Application Conflicts by Performing a Clean Startup
4. Memtest86+ paying close attention to part 3 - RAM - Test with Memtest86+
5. Hard drive test from HDD mfg website - Hard Drive Diagnostic Procedure

Good luck.

GihuNgu said:

Thank you very much. And sorry for the late answer, my baby girl was born just a few hours after I wrote my post.

In the mean time, I've applied your recommendations, especially the security software replacement. And guess what ? It solved my problems. Since then, I was able to leave my PC on for a couple of days without crashing.
Also, mem & hd tests did not show anything particular.

Again thanks for your support.
GihuNgu

Congratulations on the Baby girl :)

Observe for further issues and if you have any just let us know!