My upload start all over again.. many times

So i have a proplem with uploading..

That happened quite sometimes now..
I start a upload and everything is normal... but when its finished it start the upload all over again...
When its finished it starts all over again.. and again and again.
Problem can be solved if i use the oldschool uploader.. But honestly i want to use the new one.. where i see the progress bar and so on..

I use Firefox and the newest Flash Version...
Can someone help me please?

Regards,
Shuqq