"setup wants to make changes" keeps popping up stopping installation from starting

Hi there,
having trouble installing a trial of Adobe Premiere, every time i try to start the installation a security popup window appears saying:
"Setup wants to make changes. type your password to allow this"
i enter my password, box goes away, then reappears.
Im definitely entering password correctly as it says i don't if i don't!
my account is Admin, have tried the other account on the mac, have tried creating a new account, tried numerous restarts, tried downloading a different trial.
Same problem!!!
please help as i can find nothing in my searches... which suggests this isn't a common problem i was expecting it to be!
Thanks

MacBook Air (13-inch Mid 2013), OS X Mavericks (10.9.2)

Suggest trying Adobe forums. And update Mavericks to OS X.9.4 as there were several security updates in later versions.

Assuming you're trying to install Adobe Premiere Elements 12 trial version, have you made sure that you checked the system requirements that Adobe lists for this version? See below:

Mac OS

64-bit multicore Intel® processor
Mac OS X v10.7 through v10.9
2GB of RAM
4GB of available hard-disk space to install applications; additional 5GB to download content
Graphics card with the latest updated drivers
1024x768 display resolution
DVD-ROM drive (compatible DVD burner required to burn DVDs; compatible Blu-ray burner required to burn Blu-ray discs)
DV/i.LINK/FireWire/IEEE 1394 interface to connect a Digital 8 DV or HDV camcorder
QuickTime 7 software
Internet connection required for product activation*