[TYPO3] why not able to attach

[Bing Du]

Hi,

One of our customers reported she was not able to attach images to text w/
images type pages or not able to attach files to news items.  Every time
she had to log out of the backend interface and log back in again and then
she was able to attach.  The problem has never happened on me.  She showed
me once when she had trouble attaching.  Basically, she was able to see
the files by clicking the 'browse for records' icon but after she selected
a file, the name of the file did not show up in the image or the file box
at all.  Seemed like it had nothing to do with the type of the files.  
She also tried to clear her browser cache.

Are attached images/files stored somewhere (clipboard?) temporarily before
they are saved in the database?

Thanks in advance,

Bing