I want to update AOS to Beta 0.42, but whenever it tried to uninstall the previous version, Windows Installer would say:

"The feature you are trying to ues is on a network resource that is unavailabe. Click OK to try again, or enter an alternate path to a folder containing the nistallation package 'aos033install.msi' in the box below

User source:
[file directory]"

What should I do now?

Manually remove the AOS directory out of Program files then try installing.

Tried it, still doesn't work D:

Are you on a networked computer?

you might not be able to install/uninstall stuff.

If so, Contact your local administrator.

If your on a local PC please provide more info.

I think I'm on a local PC, considering that I'm the only person using this computer.
I'm pretty sure I'm an adminstrator in my computer(or something like that) as I created my computer account when setting it up for the first time.

What do you mean by providing info? :S I'm not really good with dealing with computers.

Download the AOS installer again and do SaveAs to your desktop.

Then open it from there.

Still doesn't work :'(