Let's start with a dose of reality. So this effort will be a bit different for both of us. Normally, I make suggestions on what to do. This time I'll be telling you what not to do. I also must say I am a bit leery about this topic, as a little information is a dangerous thing, and we are in the deep end of the pool on this one.
Mistakes can be serious in the security department.
After hours of troubleshooting, you open the case and are stunned to discover that one of the memory chips is gone. Someone has tried to hack into your machine. Or perhaps the Microsoft version is no longer 95 or 98, but something inappropriate. He or she can fix that nasty little problem for you. Each of those things has happened to me.