<p>Hi All This is a note that I just sent out. I hope that this helps those contemplating upgrading to Windows 8.1 Professional BEFORE SP 1 is released. Hi Dejan Once again, thanks for the reply, my friend. Really appreciated. The same to you Greg, Andrew and Viktor. Dejan, it was a clean install AND I formatted the disk with 8.1 thus there should have been NO residuals from Windows 7. All right, here is the issue. There is a known and reported bug in Windows 8.1 http://answers.microsoft.com/en-us/windows/forum/windows8_1-performance/windows- 81-explorerexe-sends-cpu-to-100-when/deb19e88-d95d-4e44-8678-6d033166a21f?rtActi on=1383040417676 It causes the CPU to mount rapidly to 100% and there is no workaround as yet. FURTHER , I had the CPU up at 100% for 20 minutes with NO ACTION on the laptop. Some people have attributed this behavior to the Windows task scheduler however I disabled the scheduler and the system displayed the same behavior. I believe that the same issue affects what Dejan reported to Microsoft back in October with regards to the Lift chart not working and causing Analysis Services to crash. Greg, I too created a local account and granted myself Administrators rights. My solution What I have done is downgraded to Windows 8. At long last everything is functioning OR APPEARS to be functioning correctly. Perhaps Microsoft will have the 'feature' fixed with service pack 1. Thanks again to all. Really appreciated and PLEASE pass the good word along. I do NOT want anyone else to have to go through the 'Discovery Process' that I had to do. sincerest regards Steve </p>