And I have done some reserch over the NET and found that I was not the only one with this problem. I didn't find a solution for this problem.
One guy who had this problem suggest me to roll back to Premier 6.5, I tried it, but I really didn't liked the interface. My first experience with Premiere was with Premiere PRO, so I don't want to go back.
In the mean time, I installed SonicFoundry Vegas 4.0 to do my video editing job, it's not bad at all... I found it easy to use, but I better liked Premiere PRO.
Is the file system may be the problem? NTFS is not fully supported with Premiere PRO?
Thanks, I wish you will find a solution for my problem!