I don't know what is going on. but recently i have had huge problems getting QU to open. I must have re-downloaded QU ten times. I am working on a PC Windows & professional 6GB Ram 64 Bit OS 3.3Ghz. Occasionally I have got a memory error so Have closed all other running programmes.
When I click on the QU icon I usually get a message....Do you want the following programme to make changes to this computer? If i say No nothing happens. If I click yes i get a warning saying that Qimage did not close down properly last session..Prior shutdown exit Code: 4- exist...Since you are running Windows XP (I thought I was running W7) it gives me the option to start in Normal or Safe. Neither starts QU.
I am at a loss. do i buy a new computer. QU used to run faltlessly. I run NOD all the time who claim to stop all viruses.
Jules

Thanks for getting back to me Fred. I will give this a try. The weird thing is that sometimes it does open, but about ten mintues after I had been trying! Meanwhile other progs, PS, LR, iTunes, Filezilla, Nero etc all open and work instantly.
At the moment it is running and I'm not closing it again!! How can I tell if it is running in W7 or XP? Is there a way?
Jules

Ah!!!!!!! ******  
Thank you Mike and Fred. It was running in XP. I didn't even know I had XP on this computer. I changed the Compatability to Windows 7 as you suggested and it opens immediately. How would I ever have know this was the problem without your help. The hours I have wasted not to mention hair I have pulled out  
Thanks again.
Jules