Premiere Pro CS5 version 5.0.0 freeze on startup screen

Question

MacPro4,1 Quad-Core Intel Xeon
  Processor Speed: 2.26 GHz
  Number of Processors: 2
  Total Number of Cores: 8
MacOSX 10.7.5
  L2 Cache (per Core): 256 KB
  L3 Cache (per Processor): 8 MB
Memory  26 GB 1066 MHz DDR3 ECC
Graphics  ATI Radeon HD 4870 512 MB
  Processor Interconnect Speed: 5.86 GT/s
  Boot ROM Version: MP41.0081.B08
Premiere Pro CS5 version 5.0.0
When starting app, the splash screen shows the items that are loading.
when it gets to 'loading exported quicktimehost.bundle.' It stops and freezes every time.
I can't get past this point. All i can do is force quit.
Premiere Pro CS5 loads fine only MacBookPro.
Any help is appreciated.
Paul

Answer 1

Thanks for your prompt reply, John-- and for NOT simply advising me to spend my kid's tuition on more of your company's products...
Actually, I had tried the "Run as Administrator" option already, having found it in one of those other threads;
there was no change in the sequence described above.
I decided to try another possible solution which I read about in one of those other threads: opening Premiere from a different account. 
Incredibly, it WORKED-- sort of...
I got a couple of popups advising me that missing codecs had to be installed-- and upon completion, Premiere opened!
Here's an interesting note: the last file to load was still "SolidComposite.AEX"-- and the "White Screen" I kept seeing was Premiere opening normally.  The next thing that displayed was the normal  dialog box "Open/New Project"-- I entered a new project name, and Premiere started normally. I even added a few video files as a test... all opened normally.
I returned to the Admin account to see if the fix was in here, too;
but clearly the war wasn't over, over here...
It now appears that some personal setting in the Admin account is causing Premiere to close itself;
I've been reading about the layered security measures embedded into Windows 8-- I'm suspecting the conflict lies there...
I ran the Windows Troubleshooter & got this:
both MS & Adobe confirm that CS3 is fully compatible--here's my sytem info:
Since I seem to have established a fall-back position that lets me use Premiere, my crisis becomes a mere conundrum;
but I know this is gonna gnaw at me anyway, & I'm hoping that this new information might suggest further troubleshooting options to someone who understands the Adobe software and/or the Windows software better than I do!
Speaking as someone who has found many solutions on forums like this over the years, I assure you:
for every person whose post you reply to, there are many more whom you will never know you have helped!!!