Hello everyone! I would like to ask for help from someone, as I don’t know what to do anymore.

I turned on my comp half an hour ago. It’s acted strange in the past few days, so I ran my virus scanner multiple times; it didn’t find anything though. My Op system is Vista, and my virus scanner is NOD32, the latest version, it’s completely up-to-date. After I turned on it started booting, but when I logged in it wrote out it was loading the desktop. I became suspicious then, and I was right. It started in ‘safe mode’, it looked like Win98. It blocked all the startup programs, I got a bunch of error messages saying that this and that program can’t run anymore, so I should install them again. I ran a deep scan on my comp, but at 98% it froze and wouldn’t run anymore. I wanted to reset the system, but all the reset points were gone except for two points today. Then I restarted my comp, and prepared to reinstall the Op system. However, it booted like normal, and I could log in like normal as well. Then it showed my normal desktop and I could run all the programs. What is happening? Could someone help?

ps: sorry for tl;dr