Vista - I don't where the files are going after downloading

I am having a big problem with my computer, this started about a week ago. When I prompt a file to be downloaded, save or just open, the window that normally comes when a file is being retrieve comes up and I heard the chime after the file is "succesfully" downloaded but it actually never opens. I tried to created a file on the desktop and save the files in there, and when went back to the file it was empty. I tried to restore the computer to the last good working date and I only have the current date on the restore point and that won't solve the problem, when I tried to download the Redcure program to solve the restore problem I couldn't go beyond the Run step because after I selected "Run" the window showed me the bar that goes across and it desapear and the program is not installed either. One thing I've been notice on the computer is that the disk capability increases drastically, after I clean temp files yesterday I had 1.7g of free space and today I only have 230mb free.
What I need to do beside of getting a new laptop?. Thanks a lot
Learpilot

Hello Learpilot,

Please try to scan your computer with Windows Live OneCare safety scanner: Free online tool for PC health and safety for possible viruses. Get full system scan, it should improve your PC's performance and get rid of junk on your hard disk. Hope it helps.

Cheers...