Hi,
I had the same problem in my machine having Vista operating system.
Solution: Whatever oracle client tool to use, right click on that (executable icon) and select run as administrator? Hope it need administrative rights to write some file.
Hope it helps.
Think of how stupid the average person is. And how half of them are stupider than that. But who reads this tiny ad?
a bit of art, as a gift, the permaculture playing cards