Thank you for your post.
After opening an older file in FileMaker Pro 7 or greater (including FileMaker Pro 11), you are prompted for a user name and password. Usually, Admin with no password suffices. Pull down the File menu and select "File Options", and under the Open/Close tab, check the option to Log in using an Account name and password. This will bypass you having to enter the Account name and password each time.
Closing one file should not close all of them unless you have a closing script that closes the other files. Check to make sure the files are not hidden.
Once you click on a field with a dropdown value list, you should be able to click on one of the value list items and it will fill in. Are you able to use the arrow keys?
A URL in a text field can be clickable by holding down the command key. If this is working otherwise, make sure you don't the field set up as a button to execute a script.
Please keep me updated with any additional information so I can try to determine what is occurring.
I uninstalled the programs Neu and MoveAddict, uninstalled and reinstalled Filemaker and all the weird problems I describe above went away.
I'm blaming those utilities although I didn't have the patience to be scientific and reinstall them one by one to narrow it down to one guilty party. My guess is that it was Neu. But I know I had uninstalled and reinstalled FilemakerPro before without relief. The relief came after I removed those utilities.