The problem is back, the error message "Not enough storage is available to process this command" has returned with the last update. That is getting really annoying...
The last update of what - presumably virus definitions - even if you do what was suggested by drake127 in Reply #5, I think you are likely to bump into this at some point in the future.
The reason I say that is I don't think that there has been a fix in your program version. Even if they did for some reason fix something in an older program version, how would they distribute it. It can't be distributed through normal program updates as that is tied to look for the latest program version.
To the same degree, it couldn't be done in the virus definitions and engines auto update, nor could it use the emergency update feature (I don't think that was available in your version). The problem is that all of these update functions are greaed up to deliver updates/fixes for the current program version.
I'm using the latest avast 2015.10.2.2214 version on this XP Pro system (see my signature under my post) and I don't have any resources issues such as you mention.
The other issue that hasn't raised it head, for those that are using old/outdated versions of avast, those trying to help in the forums will have long since stopped using it, so they lose the expertise in older versions.