Can't see only some of the icons on my desktop on windows 7

I have recently preinstalled my Windows, it's Windows 7 X64. When I download something it goes to my desktop. But when I tried to download some word files and looked for them at the desktop they weren't there. I clicked to download them again and I saw it's really downloading them on the desktop, not another folder and it wanted to save them as xxxxx(1).doc, which meant they were already there. I looked again, I couldn't see them. Then after a minute maybe all the icons suddenly appeared on the desktop. I found that very strange.
Then another time I was downloading a zip file. It appeared on my desktop, but then when I tried to unzip it on my desktop again I couldn't see the unzipped file and this time it didn't appear. When I open libraries or some program and try to open a file on my desktop I can see them all, they're there. But I can't see them on my actual desktop.
Do you have any idea what the problem might be and how to solve it?

Thank you, that helped and all the icons appeared. But does that mean that I'll have to do it manually everytime?

Yes, it helped, but I still have to do it every time and it's annoying. Is there a way to fix it?

Try creating a Download folder in the root directory (C:\)and setting your browser to send files to it. This is what I do with every machine I set up. I never use the "Downloads" folder. This will keep all files downloaded off of the Desktop and in a central location.
Once you have moved all downloaded files to the folder-refresh the desktop icons. I would also suggest that you run Ccleaner to insure that all is otherwise OK. (Some argue that this program is not needed-I use it all the time.)