Iv been on 40mg for a year now i could be feeling perfectly fine ...

Your complaint of "intense tiredness" is likely statin induced heart failure, described in the following article. Dr. Peter H. Langsjoen, MD, FACC, Board Certified Internal Medicine and Cardiovascular Disease from Tyler, Texas recent article in LifeExtension Magazine (February 2008) describes in detail the trouble with statins http://www.lef.org/magazine/mag2008/feb2008_Alleviating-Congestive-Heart-Failure-With-Coenzyme-Q10_01.htm, “All statin drugs block the biosynthesis of both cholesterol and CoQ10, which explains statins’ common side effects of fatigue, muscle pain and muscle weakness, and a worsening of heart failure. When CoQ10 levels are lowered by statin drug therapy, one of the first changes to occur is a weakening of heart muscle function… In 2004, a study published in the American Journal of Cardiology showed that diastolic dysfunction (heart muscle weakness) occurred in 70% of previously normal patients treated with 20 mg a day of Lipitor® for six months. This heart muscle dysfunction was reversible with supplemental CoQ10. Heart failure that develops after years of statin drug therapy can be termed statin cardiomyopathy and may well be playing a role in the epidemic of congestive heart failure in the United States.