Help required on Brodcast messages to logged on users in Portal- Weblogs

Hi All

The link to the weblog is

Brodcast messages to logged on users in Portal(Part1)

My doubts is

1) Whenever user refreshes his/her page the popup gets displayed.

User might get irritated everytime he will referesh the page.

2) When does the data stored in container destroys?

Please comment

Points will be rewarded.

Regards

Sonal Mangla