I need help in fixing a persistent issue with my computer

[Shadow]

It all happened once when I was typing the password to my account in order to log in. I was surprised to see an error saying "initialize.exe encountered an error and could not load. Do you want send a report about this?" after that. Then, I noticed that all my personal settings disappeared; I have a blue background now, my documents and music are gone, the Zune theme is gone and currently I only have 2 lists of icons on my desktop. I think this is the safe mode of my computer (which runs Windows XP), but I still want to describe the situation in as much detail as possible.

The problem only gets worse than that, as I also cannot:

1) Open PDF files using Adobe Reader. (I get an error titled "Microsoft Visual C++ Runtime Library" which says "Runtime error..." and then my computer freezes for a short while)

2) Save documents in Microsoft Word. (Whenever I click 'Save' and then quit, I'm asked whether I want to save the changes. Even after clicking 'Yes', I'm still prompted the same thing when I want to close it. Due to that, I am forced to use Word Pad instead)

3) Open things like Windows Live Messenger. (I click it, I get the hourglass icon for a split of a second, then nothing happens. After trying to open it another million times, it just doesn't work and nothing happens)

4) Scan documents from the printer into the computer. (May have been from before, but I'm fairly sure it wasn't present before this time)

Is this an issue which I can fix by myself, or do I need a professional someone to format/fix it for me? I can probably describe more details if you specifically ask me to, and I'd really appreciate any sorts of help.

[Winter]

If you have your XP disc, I would wipe it completely yourself. It seems as though you might have a virus possibly if you are not in safe mode.

[Shadow]

Ah, I thought I had a virus, too, but I was (and still is) not sure of it. Thankfully, I was able to locate my documents in "C:\Documents and Settings", so I took a quick back-up of everything I need. Since I don't have the Windows XP disc, I'm going to format my computer and install Windows 7 on it. Nevertheless, thanks for the help, Winter.

*Locks thread*