Uninstalled/reinstalled FSX clean, rebooted, then just ran SP1 exe. Do you think it can potentially bear some problems since I didn't run FSX which did not create the necessary cfgs files and settings?Thanks.

Not at all - this is exactly how I and many other users have brought FSX SP1 into the world, and it works just fine. In fact, I'd personally recommend this way because it nearly guarantees that no CFG file updates or changes will have any bearing on how the service pack is installed.No worries at all. :)-GG

Thanks greggerm, now I can finally enjoy the sim happily, instead of reinstalling it again in search for something don't know what. :)