I Have A Virus That Is Hiding Files Redircting Web Searches And Generally Making My Life…?

First of all I don’t know a lot about computers but I can generally get rid of a virus this one however I can’t so I’m looking for help getting rid of it.
I have no idea where it came from someone else used the computer then it was messed up.
This is what it is doing…
First my trend micro internet security messed up it asked for the password every 30 – 60 sec I was getting pop ups that trend was blocking.
Then it wouldn’t load (blue screen of death) finally got it up in safe mode ran a system restore, it would only let me go back 2 weeks even though I had points farther back.
After scanning and a restart everything was gone except the recycle bin.
Another system restore got that back but I ran avg adaware and malaware bytes got rid of probably 50-75 trojans over the course of a few scans a restart took me back to the blue screen of death, more trojans more disappering files/icons.
Obviously I went back and forth with all this a few times. I had to uninstall my Trend because it was causing alot of problems with the password thing popping up so often, if the computer wasn’t being used it was fine but anytime you tried to type it popped up.
All of the software stopped finding viruses and I decided to go looking for my files, they are all set to hidden so I went to work unhiding them. I’ve got back some of my icons but I can’t click them. I can’t even highlight them. I can click on my start menu I got a few things back on it but I can’t click on anything in the start menu. I can run anything on the toolbar I can even get into the toolbar properties but I can not do anything on the desktop its almost like its just a picture if that makes sense.
If I do a web search like on yahoo or google about 80% of the time I will be redircted to a diffrent site when I click on a search result however I can type the address or copy and past it and go directly where I wanted to go.
If we leave the computer alone for a while I start getting popups most of them are for something called meevo sometimes a site that says meevo and sometimes its just their terms and conditions but I can’t find any type of program or internet history showing that one of us actually meant to go to this site. Apparently this is what was being blocked by Trend as my parental controls will not allow this type of site.
The last time I tried to restart the computer wouldn’t come up for a day or two not in “normal” mode or safe mode then it just did but its still acting up and still no icons except the ones that I just put on the desktop that won’t work. And I stress the desktop will not work I can’t even get a menu from right clicking.
Does anyone have any idea what this may be and how to get rid of it, I use my computer for my business and I really need it we just opened and are having a hard time so I really don’t need this.
Sorry this was so long I wanted to make sure that I provided enough detail to get some help with the issue.
By the way I have a Dell XPS M140 and I am running Windows XP Media Center.