Build Configuration Page stops responding in Mozilla 5

Hi,
I am using TeamCity 6.5.1.
I encountered problem with TeamCity build configuration edit page in Mozilla firefox 5.0.
The page did not save the changed configuration . I closed the browser and reopened  it still the problem persisted.
Only when I deleted the cookies that page started saving the change.

Can you please let us know what might have such this odd behaviour and how in future can we prevent such thing from happening.

Regards
Ruby