Even with just one user (which is my case as well) there is still an administrator account. If you right clicked on a command window and selected "run as administrator" then Fritzing will install as administrator (someone else did this and had problems), but it doesn't sound like you have done that. The error message isn't particularly informative, but it does appear incorrect in that the path shouldn't be C:/User/simon/Desktop/Fritzing/fritzing.0.9.3.b.64.pc but something like C:/User/simon/My Documents/Fritzing. It may not be allowed to right in to the distribution directory. What I'd suggest (assuming you don't have any sketches yet, which it sounds like you don't) is deleting the program and the user directories and reinstalling fritzing. When fritzing first starts it goes to github to update the parts database which takes a long time and appears to be hung. If you interrupt it, you get odd problems possibly like this one and the only solution is to reinstall the program. Below are the instructions to clear the user directories (which a reinstall of the program won't affect):
There are two user directories (with your parts and the parts database) which don't get touched during an install (to not affect your sketchs during upgrades). On Windows they are in
c:\users\username\AppData\Fritzing\roaming\Fritzing (which is a hidden directory so you need to enable hidden directories in explorer) and
c:\Users\username\My Documents\Fritzing (where username is your windows id)
If you don't have any parts or sketches you want to keep you can just delete those two directories and Fritzing will receate them, or you can move them aside by renaming them if you wan to keep something in them.