I can only recognise one of the issues you have noted ... the refresh/search page problem.
I've noticed that with the newer browsers search pages cannot be "backed" into or refreshed due to the nature of what they do. Screen 1 asks for a search term, Screen 2 processes the results and delivers to Screen 3. Screen 3 doesn't tend to record in its url what was on Screen2 so when you back into Screen3 (from the page you loaded from the search results) it doesn't have any search criteria to load and thus fails. You can normally refresh the same page and get your search results back. Google Chrome browsers displays this page when you try to go back into a search page :
Quote:
Confirm Form Resubmission - This web page requires data that you entered earlier in order to be properly displayed. You can send this data again, but by doing so you will repeat any action that this page previously performed. Press Reload to resend that data and display this page.
As for problems logging into forums is this browser specific ?