My PC was functioning perfectly until a few weeks ago when it started slowing down significantly. It now takes around 15 minutes to boot up, and many applications won't open. After consulting IT, they suggested upgrading the RAM. I replaced the old RAM with a new 32GB kit, which improved the speed slightly, but the PC still faces several issues. Upon startup, I encounter a 'Microsoft Windows is not responding' error, and I have to wait for everything to load. Even after that, I can only open a few applications and struggle to access files. Occasionally, the system freezes with a grey background, requiring a forced shutdown to resolve. What steps can I take to address these issues?