Shut Down Problems?

I have an ULTRA windows 98 pentium 2 thats been seating around for about a 1 1/2 years. About a 1 1/2 year ago i turned it on, and got this error [SK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER" , and never had it check out. I know its old, but what im going to use it for, it will do fine.

What i have done:

I unhooked the cd drive, and flopy (nothen was in them first thing i checked). Then i took a wire thing that go's from the hard drive to the motherboard of an old comp, and put it on the computers we or talking about hard drive, and pluged it into the motherboard.. Then turned it on, and it started right up with no error.

I dont know what the problem was, like if its the wire things, or the cd/flopy causing it?

Now heres the new problem:

I can boot it up to windows now, but it shuts down or i get black lines going down all the way across the screen? I know its not over heating because i check that first. In safe mood it stays up longer, and when i boot it up in not safe mood it some times boots up to the desktop, and then a few mins shuts down/lines. Other times it wont boot up to desktop, but restarts lol. What could be causing this, maybe a file that as be donwloaded on it. I know its not virus, because i scaned it.


Thanks