Pc freezes and bsod

Hey. I have been experiencing some freezes in my pc lately. What happens is that my pc freezes completely and i can't do anything( for example the mouse won't move, and ctrl-alt-delete won't do anything). This happens most of the time when i turn on the pc and after some minutes I play a game( League of legends in particular) or watch a video on youtube. It has also happened when switching tabs on google chrome and while using msn messenger.

I also experience bsod. These happen when i am starting a video call on msn messenger. I have never had a bsod while using skype although.

My pc is 4 years old and last year i bought a new graphics card and i added 2g ram.
I use windows 7 professional 64bit.

Thanks in advance.

thanks for the quick response. i have reinstalled the drivers and software and tried some video calls with msn messenger and no bsod happened. in case a random crash happens again i will inform you.

thx panai =P

hey there again. so yesterday after i did those things you told me to, i made some video calls with msn messenger and no bsod happened. so it seems that 1 of the problems is solved.

but some minutes ago, my pc freezed while i was using google chrome and windows media player. i am sending the zip with the files of the system health report and the BSOD Dump & System File Collection app.

well i have a keyboard and mouse set. it's logitech Cordless Desktop® EX 110. i don't have any usb keyboard or mouse.. so can i just uninstall and reinstall the drivers and software of my set?

i uninstalled the software and the drivers, and then i unpluged my set. when i was plugging it in it didnt recognize the set. so i putted it in an other usb port and it did recognize it. so i installed the drivers and software again. in case another freeze happens i will inform you. thanks for the help