hello everyone. my pc start hanging i dont know why? plz help i am not master in pc. i use win 7 32-bit and no antivirus i yet installed. i reinstalled win last week
More info WOULD be helpful:

Computer make/model
How much Memory it has

*Was this problem present prior to the reinstall? Were there any hardware CHANGES to this system that lead to the current problem? Was the reinstall because the prior build was infected with malware or a virus? Did you perform a full reinstall deleting all data from the drive or a reinstall that SAVES all your important data also known as a system recovery repair installation?

Why not run an antivirus?, there are good free ones available. I use Microsoft Security Essentials as my free antivirus.
DaveLembke,, thanks for help

computer model: G31T-M7, ram 1 gb, hard disk 500 Gb.yes, problem present prior to the reinstall.
i dont about any hardware changes to lead that problem.
yes, i reinstalled bcoz pc hanged to much may be due to virus bcoz my friend used
his pen drive on my pc without scaning..
full reinstall or not i dont know how to do that,i describe u what i did.
i just put win 7 cd in cpu and follow step without TAKING any back up.
i was also used microsoft security essential but due to window genuine problem, it expired.
today a msg on appear screen when i start pc ((((Problem Event Name:BlueScreen)))
what is this and what it mean?
The fact that you are not using an anti virus app and have symptoms that appear to be viral should be indication enough that you need to format, reinstall a genuine version of Windows from a retail Windows CD, and IMMEDIATELY install an anti virus application.