I originally had this problem with a Dell Inspiron 518 Vista Home Premium tower Unusual & Perplexing Page Not Found Behavior
I decided to reinstall the OS, but I could not get the PC to boot off the CD - F12 to change the boot order or F2 to access Setup did nothing. So I ran Windows Vista setup from within Vista which created the folder Windows.old on the C: drive.
The first weird wrinkle was that I could not access the internet - the was a yellow ! on the network adapter in device manager. Uninstalling it and letting Windows reinstall didn't help, so I downloaded what Dell said was the correct driver - Realtek RTL8168C (the one w/ the yellow ! lacked the letter C). Once I fixed that I could connect.
Then I noticed that I couldn't right click on an empty area below the address bar in IE - I wanted to get the Menu Bar and remove the Favorites Bar. Right clicking did nothing. The mouse works fine, and I can use the right mouse for other things - right clicking Computer, then left clicking properties, righ-clicking a document, then left-clicking Explore, or Open, etc.... I did get the bars fixed by left clicking Tools, then Toolbars, and checking and unchecking what I wanted, but right-clicking on the Menu Bar still does nothing.
I also cannot send shortcuts anywhere. I used to click File\Send\Shortcut to Desktop to get a desktop icon for my email. I can do those steps, but no shortcut appears. I had to drag from the left of the address bar to the desktop to create a shortcut.
I cannot open a folder anymore without it opening in a new window - the option in Control Panel/Folder options is set correctly, and I even checked the registry. I dunno - it's got the right valuesin CabinetState.
But the biggest problem is that I cannot download... usually. I easily downloaded Security Essentials, but when I tried to downloader Adobe Reader X nothing happened. No little clickable bar below the tabs line at the top, no download box. Same thing happened with Malwarebytes from CNET. That one l downloaded using a thumb drive on another PC. It installed perfectly, and found no errors on a full scan.
I also ran sfc /scannow which found no integrity violations.
Do I have to reinstall again? And how do I do it (see paragraph 2)?