Hi VAMOS,

A program crash is not unusual, but programs that crash often is unusual. So beginning with the crash event, do you have one particular program that crashes often, or different programs that crash causing a locked situation that Task Manager can not resolve?

Off the record, I highly suspect that random lockups are caused by a hardware configuration problem. Since no two personal computers are alike, the problem you experience seems to have started with the upgrade from Windows 8 to Windows 8.1.

There are some known issues with the upgrade and OEM built computers. If I were you, my first check would be to ensure that all devices as viewed in device manager are functioning properly. This means there is no yellow warning icon next to the device or device unknown errors.

It is always advisable to re-install all of the DELL CHIPSET drivers once a new operating system has been installed.

Hope this helps

To add to what manydimensions said, when you updated to Win 8.1, did you update all drivers to their Win 8.1-compatibile versions?

Go here and change the OS setting to Win 8.1 and look for updated drivers for your hardware. You only need those drivers that are specific for the hardware actually installed in your system.

Sorry lost track of my post here.
The crash is with several programs: Winamp, Photoshop, Illustrator, ... Once it freezes I can't end it in the task manager. I've had a look at the device manager but everything is working OK, should I try to update all drivers? I am a little bit worried it will bring more problems...

I don't think it's a memory issue. I have plenty of RAM and it's always at 25% or less. How can i run a full diagnostics so we can be sure?

Have you run full diagnostics to rule out any memory issues?

How much is free doesn't tell you if any of it is bad.

Reboot and press F12 before Windows starts to load. Go to Utilities partition where you'll find the option to run hardware diagnostics.