I need help: Desktop will not run only get a blackground

When I start up my computer and login to my account my computer desktop does not show up. I get a black background and a documents window opens up. Everything on my hard drive is still there but my desktop won't run unless I go to the task manager and enter new task explorer.exe and then everything runs like normal. It could be a registry problem but when i got rid of the virus in my registry everything was still the same. I need help trying to get it to run normally.