Autocomplete Text Input - display area not visible


We are now migrating from 7.1.3 to 8.2 and have found a problem with the Autocomplete Text Input display on the details page of a task.

The scenario is as follows:
1. go to the details page of a task
2. select a value for the autocomplete control
3. save the changes for the task
4. leave the details page
5. return to the details page

As you can see in the attached image (autoCompleteDisplay.png), the display area of the autocomplete field seems to be covered by white rectangle.

We have MWS_8.2_SP1_Fix7 installed.
The bug reproduces on both IE8 and Firefox 9.

Has this problem happen to any of you?