What are the common information technology project problems?

zfbfb People Forgetting PassWords Operating system getting old and unstable needing to be reinstalled internet explorer crashing, malware taking over computer Can't connect to a computer, slow computer startup My question is when you use a recovery disc on somebody elses computer it won't let you because that disc is not intended for that computer it has a different OEM or something like that. So what does this mean, does it look at your operating system product key and say this is a different computer or does it look at your motherboard or something else???