If you've set up a User account, I suggest you try installing from an Administrator account.

I'll disagree a bit and say that defragmentation never helps and never accomplishes anything beneficial, and are a lot of unnecessary wear and tear on the drive.

Registry cleaners often do more harm than good, since they really don't know what's actually supposed to be in the registry or what is safe to remove.

Yes, sometimes you might just happen to have good things happen with them, but the norm is that they do nothing useful and are potentially harmful. You'll accomplish a LOT more good simply by rebooting.

If you delete a large number of files or otherwise defragmentation really helps to speed up your HD access time. Been doing this long enough to know, since a Radio Shack Model One anyway.
Registry editor or tune up. I agree unless you really know what you are doing it can screw things up big time. Use with caution.

Actually it doesn't help. Not at all.

Lots of real drive speed tests have been done over the past couple decades comparing fragmented vs. non-fragmented drives in all sorts of situations. Not once has a defragmented drive ever been shown to perform significantly faster. In fact, in almost all cases there was no measurable difference in speed at all. There are so many other factors in play besides moving the head around that have a much larger effect on drive speed that fragmentation doesn't even register. The only reason that some folks think they've had an improvement is because most of them have done a reboot afterward, or have shut down other programs that had been running.

I've also proven at length before that in a typical AV media editing scenario a defragmented drive is actually LESS efficient for file access than a randomly fragmented one.

In short, defragmenting is a myth and potentially harmful. Just forget about it and don't do it.