Different frets show different fine tuning

I have an Ibanez guitar with a tremolo. When I tune the guitar, it sounds perfectly in tune when on the lower frets, but when I go to the higher frets (around the 12th), it sounds out of tune. If I tune according to that, then the open strings and lower frets sound out of tune. This always happens with me when I try to play the main riff from Sweet Child O' Mine. I want to know what exactly causes the problem, and how it can be fixed, and whether I can do it myself or I need to go and show it to a repairman.
Thanks
Ameen

Your intonation is off.

Have you changed your strings since you encountered this problem? If not, you should. Gunked up and corroded strings can cause this.

If a fresh set of strings doesn't cure the problem, the intonation screws on the bridge need to be adjusted. You can either google "adjusting guitar intonation" to find out how to do it, or take it to a tech who can do it for you.

One more thing:
When I use the whammy, the guitar goes out of tune. What is that related to, and what is the solution?

The strings are probably binding in the nut. The nut slots may be too narrow. The nut slots may also need to just be cleaned out or lubed. Graphite dust from pencil lead works great for that.

I did try lubing the nut. It did not work.

Originally Posted by: ameen_s23When I tune the guitar, it sounds perfectly in tune when on the lower frets, but when I go to the higher frets (around the 12th), it sounds out of tune. If I tune according to that, then the open strings and lower frets sound out of tune.[/QUOTE]
It's either too high action, intonation, old strings.

1. High action. The bridge saddles need to lowered to the point that the higher frets are in tune, but not so low as to cause fretbuzz against the strings. Action or string height does has an individual preference range. But at a certain point if the strings are too high, then the distance you have to press the string down to the fret causes you to bend the string too far & raise the pitch!

2. Intonation. The bridge saddles have to be adjusted back (lengthened) if the string sounds sharp on the upper frets (higher in pitch), forward (shortened) if the string sounds flat on the upper frets. The precise way to do this is to match the 12th fret harmonic with the note fretted at the 12th fret. The 12th fret harmonic is always right (assuming clean, fresh strings!) so that's the standard. So the fretted note is the one that will show if the string is intonated.

If this task is beyond your skill set, take it to your local music store & ask them to set the intonation.

3. Old strings. Sometimes old, dirty, worn out strings can cause tuning issues. And it's always a great idea to put on new strings before you set the action & intonation.

We have tutorials on that here.

http://www.guitartricks.com/tutorial.php?input=1974
[QUOTE=ameen_s23]
When I use the whammy, the guitar goes out of tune. What is that related to, and what is the solution?

If you have a guitar with a standard vibrato system, a non floating system, then this tutorial has lessons on that!

http://www.guitartricks.com/tutorial.php?input=1219

Ask more if necessary & best of success!

Thanks a lot for the help, the intonation problem is more or less over. However, the whammy problem still exists. My guitar does have a floating tremolo system, and I observe the problem the most while playing Eruption by Eddie Van Halen, after the first section.The guitar that I have is and Ibanez GIO GRG170DX, in case you want to check it out, I'm having a feeling it might contain some answer.
Thanks again
Ameen