Just three days ago I began having trouble with my computer. I logged in fine, checked my email (I didn't see anything malicious or suspicious) and then tried opening Firefox. I was told I could not connect to the internet. I restarted my computer, logged in, and several warning pop-ups began flashing. I unfortunately did not check to see what they said but instead tried to get to my anti-virus software as quickly as possible. I unplugged my network cable and ran AVG. After a full computer scan, it told me I had no viruses. I figured the warning was just a small fluke with my computer and ran the rest of my daily tasks - the only sign of concern was when I opened Photoshop and an error appeared; I do not remember the exact wording, but something along the lines of Windows and a bad image. I shut off my computer, and ever since, I cannot log back on. It brings me to the welcome screen, but the log-in field never appears. I have waited for over an hour and have restarted my computer several times, but it never appears.
I hate to say that in my panic, I did not back-up any recent, important files. A huge weight will be lifted off my shoulders if someone can show me a way to log-in long enough to back-up some files. Once that is done, I'm willing to reboot Windows if necessary to get rid of any virus (although I would rather not). Any advice would be greatly appreciated.