I have installed Avast on my D drive but of course some of it will go on the C drive since that is my system drive BUT the problem is that I use a thing called Deep Freeze which freezez my C drive so everytime avast updates I wonder if it really is updated or if it just updates everytime I reboot with the same update.
Any chance of avast making a portable version that allows us to have it on the D drive only?
Hello 
I don’t think that this can happen (this is only my opinion), because an antivirus program have to be integrated in the OS, so it can work properly. Maybe there can be a portable version, but without a Resident Protection.
Well, if avast! is updating without any error messages, and everything is working fine, then I think that there is no reason for panic 
Yes, I’m afraid some files (such as the resident protection drivers or the boot-time scanner executable) should be in the system folder.
Well I too have avast on my D drive and for the most part the updates only effect that drive, VPS and Program updates normally effect the files in the avast4 folder. Yes on program updates it may be possible that some of the files in the system folder might change but, program updates aren’t that frequent.
You could also do what I do (because I’m on dial-up) don’t allow automatic updates, have avast check and ask permission if an update is available. That way if there is a program update you could pause/disable the Deep Freeze, do the program update and enable Deep Freeze again.
Sorry I don’t have a clue how Deep freeze works or if this is an option but, avast isn’t that much from many programs, you only have to take a look in the C:\Documents and Settings\UserName\Application Data\ folder to see what I mean and this doesn’t even include those programs that place files in the system folders. Nor does it take into consideration the registry entries which are in your C: drive.