Hello matata,
Off the top of my head there are about 3 most common issues that would cause Windows Explorer not to respond.
1. Software; The functions of some applications may attempt to perform actions or access resources that Windows cannot understand. Update any and all 3rd party software to the most current version.
2. Drivers; Drivers are extremely important and are in constant use while the system is powered on. Drivers have a high rate of opportunity for failure. Update your device drivers.
3. Overheating; Make sure your inside is free of dust and the case has good air flow, make sure your fans are working effectively, especially the CPU and the video card.
You may want to run SFC /scannow...