Yes, but that doesn't necessarily mean that avast! has a problem. It could be that something went wrong during installation process and that's why mail scanner is not working as it should work. Of course disabling that feature would help her send/receive if it's not installed properly in the first place.
Try as I said... uninstall avast! completely. Use this tool and read instructions please:
http://www.avast.com/eng/avast_uninstall_util.htmlReboot your system even if it's not required. After that, go into Outlook Express and check if everything works properly now when avast! is completely uninstalled. Just to be sure.
Then, when you are sure everything works properly, proceed with avast! installation. Everything should be OK.
Another thing that just came up to my mind... is she user with administrator or limited rights on that computer ? It would be much better if you can log on as ADMINISTRATOR (not just as some user with administrator rights, there is a difference) and then install avast! from the scratch.
Cheers !