Normally i use Microsoft Security Essentials on my System w/ Windows 7 Ultimate 32Bits,but i decided to try Avast Free. The problem is that,when my PC goes on sleep mode n comes back again,i get a blue screen. A friend told me that thats normal,because Avast can't work properly during sleep mode,but Essential always could without any problem... So guys,what's the deal here? Do you think it's totally normal or something about the Avast version or what?!
It may well be the Avast, try uninstalling it and using MS Security Essentials again to test and see if the problem goes away. If the problem is solved, you can stick with MSSE or try another different product.
Hopefully, you uninstalled the old MSSE and were not using two antivirus programs, as that too can cause issues.
I've seen this problem quite often on home built systems. It has to do with a driver conflict. Sleep/Standby and Hibernate are very driver dependent. Sometimes you simply cannot get a combination of hardware drivers to work together with those modes. Anti Virus is a possible cause, if they use a third party firewall since that does create a virtual driver to run the firewall. Since MS Security Essentials uses the Windows Firewall you could try switching to that. Only other thing I can think of is verify you have the latest version of drivers for all your hardware.