Vista - downloaded and installed programs disappearing after shutdown

I am having a problem with programs that I had downloaded, installed and used disappearing on me the next time I turn on my computer. When I go to the shortcut and click on it, it tells me "the program or file this shortcut refers to has been changed or removed". This is getting extremely annoying. I am unsure what is going on. I am running Windows Vista Basic and Norton 360. This is a brand new laptop (purchased in the last month).
This has been going on for about a week or so now. When I first brought it home, I had no problems whatsoever with downloaded and installed files disappearing, now it seems that every time I download a program this happens. What can I do to fix this? I also have installed Norton 360 on my Windows XP laptop and haven't had this problem there. I am guessing it is a Vista-only problem. Any and all help to fix this will be greatly appreciated.

Create another user account and login to that account. Check whether this is happening in that account also..

Next time you download pay attention to the folder. If you somehow changed it to a temporary folder, then the next boot Windows may be deleting the stuff. Try making a folder C:\download and saving stuff there.

Also if you are using a download manager the default folder may have gotten changed and you don't see it if it downloads automatically.

All games and dowloads are either downloaded to a specific file i.e. games or to the desktop. Big Fish Games has its own download manager. The games that I downloaded when I first got the system are all there. It's the ones I have tried to download in the last week or so that keep disappearing when I restart my computer.

Okay, went into user accounts and turned off the UAC control and the latest download didn't disappear. Looks like that may have fixed it. I'll keep my fingers crossed and hope that it continues to work. Gonna go try and download some more stuff and see what happens.