It all started with SHDOCVW.dll.....PLEASE HELP

Hello, I am new here and hope to get the help I need.

I have a Inspiron 600m with Windows XP pro , bought it in July 2003. with my own money and everything was going just awesome and I loved my laptop until a week ago.

I closed the laptop as normal before I went to bed and when I woke up the next morning,I logged onto my account and a message popped up reading exactly this: This application has failed to start because SHDOCVW.dll was not found. REinstalling this application may fix the problem.  and my desktop was blank no icons no taskbar nothing the only thing I think of to do was control ALT delete so that the task manager would pop up but anyway I could not figure out what to do. So I called DELL and they suggested a System restore, which I had no problem with,unfortunately it would not let me do a system restore  because the only day that was able to be clicked was that current day and that wouldnt work because its the day things got screwed up. So the guy said since that didnt work, I would have to reinstall Windows. but he asked me if I wanted to do a Partial re installation or something where, I would reinstall it but keep my files but in turn I would always have a "broken" windows there and this would take up space. Or if I wanted to do a complete Reinstallation that would clear out the computer deleting all the files but only one good operating system would be there. I didnt mind deleting everything so we went ahead and did the complete reinstallation. So that was fine. SO this week I went ahead and reinstalled all my software and programs that were deleted. Now these are the following problems I have, I dont know if they relate to any of this or what, BUT NONE of these were a problem before My laptop ran PERFECTly before.

IT IS SLOW. Dont know why. shouldnt it be faster? since I had to delete EVERYTHING even the messed up operating system?

Today Logged off my username to find that a new user name was there called Support. I had NOT made a new account. I had no idea where it came from.  It even had a password. Which of course I didnt know. So I just went to user accounts and deleted it.

I get one pop up a day from this pornstation.org. I have never looked at porn yet this pops up, It does not  have pics but its not even an internet explorer pop up its a Messenger window . so I think I fixed it my self by disabling the messenger by typing services.msc in Run in the start menu but I dont understand how that came about in the first place.

The computer makes a funny noise like a  squeaky pop when Iisten to music or even talk on AIM , It is especially bad on my headphones.

The Mcafee and Norton are not working properly. I open the program but it closes before I can even try to click something. I try it several times before giving up because it will not stay open. And I am especially worried now that a virus is going around in the email. I just want to make sure I am protected.

Also I get this System Shutdown message that pops up. It shows a countdown with about 50 seconds on it and then the computer shuts down. One time it happened while I was trying to open Mcafee another time just when I was surfing the web.  I think it said the Remote Procedure Call service terminated and to save all files because the system will shut down in however many seconds.

And every one of these problems shows up in my Error log in the DELL solutions on the start menu. There are no errors before the date Friday January 23rd 2004( the morning I opened my computer and the desktop was blank, the day it all started!) and the errors are just becoming more and more in number. 

I'm really frustrated because it seems that whatever I did only made it worse. Very soon am I going to check my warrenty to see if it covers being sent a new system unless I can get some help here.