I recently installed avast 4 free home edition. I have windows me operating system. When I try to run a scan after it scans about 600 files I get a blue screen and my computer needs to be restarted. Why is this hapening? I cant even scan for viruses.
Forum members who might be able to help you will want to know the name of any other antivirus product you have (or have ever had) on your computer. Also the name of your firewall, if you have one, and any other security programs you use, such as Spybot Search & Destroy, AdAware, etc. If you would post this information, it will help them to help you. 
Can you copy the message and post it here? Specially the error description and numbers, name of the driver that failed.
I get a blue screen that says exception errror OE has occured at 0028:E4257EFD. Then press any key to continue. If I dont hit anything another blue screen comes n that says Error has occured VMM(12) + 00002B7F Error OE 028:c0281B7F then computer restarts and another blue screen comes up…finally I get a windows protection error. I have had AVG & Bit Defender programs in the past. No spyware or firewalls.
I won’t be surprised if AVG was not correctly uninstalled and its email plugin is conflicting with avast…
Can you boot in Safe Mode and clean Windows registry from Grisoft or AVG keys?
Maybe you can find many free versions of these registry cleaners here: http://www.snapfiles.com/Freeware/system/fwregtools.html
Did you try Googling the error numbers?