Well that's the way MS designed UAC. We can't do anything to make it learn. Perhaps Win 8 would be better.
Your file system has errors. Run chkdsk /f on all your partitions as already posted in #2.
Now its showing FF 7.0 as the current release.
UAC is for your own safety. You can turn it off but I would strongly advise against it.
And its much faster than previous versions. Seems that Mozilla has finally gotten grips over the RAM issue.
Firefox 7.0 has just been released. Downloaded & installed it. No real problems till now except the add-ons.
Separate names with a comma.