Hello2007 asked a good question here
it seems fishy because if it is what it claims to be why isn't it popular, i was looking at bufferzone but they want money from you
You are wise to be careful. If it seems too good to be true it probably is. Derned if I know why they aren't more widely used.
The claims they make probably can not be taken literally...nothing is bulletproof...but I can say for sure that I have used all 3 (with WXP home on a fairly fast machine) and they work great. No conflict with any AV, malaware app, or firewall I've ever used except A-Squared. Nothing wrong with A2, it is just too restrictive to suit me.
From a not very tekkie point of view, I've noticed a couple of things worth mentioning. Hope some other members jump in here and comment.
Returnil seems to slow the operating system, but only a little.
Returnil only claims to protect the system partition. Not sure how important that is.
I don't use it much, but DennisD has much experience with it.
He has probably used a later version than I have.
Powershadow does not seem to slow up the system.
PS claims to protect all partitions on the HD, but I'm not sure if it does.
The first reboot gave the message that "windows has recovered from a serious error", but everything worked fine after that.
Version 2.82 tries to phone home after 30 minutes on the 'net, but you can easily stop it with your firewall.
Don't think v. 2.6 does that, and you can't get ver 2.82 anymore, so maybe its not an issue.
Also, v. 2.82 seems to write something in the zero sector of the HD which survives reformats. Worries some people, but apparently does no harm.
Sandboxie traps things in the sandbox, which is a sort of a folder in C: drive.
From reading around the 'net, it seems that things can escape the sandbox. You'll have to look for yourself, I don't have the references.
Doesn't matter, I use Sandboxie and powershadow simultaneously. If something gets out of the sandbox (never has), it is gone on restart.
Very nice feature of Sandboxie is that whatever is in the sandbox is visible. You can delete it at any time, whereas Returnil and Powershadow only delete changes upon restart I think...not sure about Returnil.
Bottom line, I guess, is that if you have one or more of these running, you are well protected against unexpected changes to your OS. I have tangled with some bad bugs, and come out OK after restart. So far.