Had a virus and didn't even know it!!

Last week I was working on some Anniversary invitations and the paper got stuck in my printer(because I forgot to change the paper settings to card stock) But after I got my paper out of the printer and started over, it kept giving me a weird error message. Something like project can't be delievered to printer. So I decided to reboot, hoping it would fix it. Well when I turned it back on, all I got was a black screen telling me to put in cd to reboot.
I was soo upset! I worked for hours trying to get it back up and running with my 3 restoration cds. Every time I would try to reinstall my windows(ME) it wouldn't let it finish the installation. It was sooooo messed up it wasn't even funny!!
Finally after about 4 hours of working it finally loaded and I was able to get back to my desktop. I was unable to get into my computer at all! Couldn't even get to my desk top or toolbar..
Every thing was fine for about a week, then I came in here Wednesday and started to check my mail and it wouldn't do anything!! (I usually leave my computer running still signed on to aol but I turn off my monitor) I turned the monitor on, wiggled my mouse...and nothing!! So I thought well all my tricks didn't work in order to get it to come on. So I turned it off and then back on again.........
YEP you guessed it! NOTHING but the same black screen!!
I was right back to where I had started from!
So I again went thru the same steps in hopes of it fixing it. It took me thru totally different steps than it did the other day. Then it popped up with NORTON! saying I had a virus in C:/java:script/ something something something. So I don't know exactly which virus I had, but it is fixed now thank goodness!!
So is there a virus that you can have and not know it until you reboot??
Also while all this was going on and I was trying to fix it, my mouse wouldn't move! I had to make my way around the screen with my keyboard keys.
????? Anyone know what this could have been??