cant change router settings

i have a small server running on my home network and it has always worked fine but the other day i cleared my router settings and am having problems putting them back. i have a linksys befsr41 router. my problem is this: i have set everything back to the way it was except for th filters. for some reason it wont let me change the filters such as block WAN request and filter internet nat redirection and so on. when i pick the setting i like and click apply i get a username and password prompt. no matter what i type in it just keeps popping up. i know its not a password problem, i really have no idea what it is though. ive changed firmware several times, reset to defaults and changed the password, nothing worked.

UPDATE (not that anyone seems to care)

i installed a diff browser from the host computer and now i can log in but still cant change the settings. help plz. anyone?

If the password prompt keeps appearing it is usually a bad username/password.

nah cause i can log in and change the password if i want the only seeting i cant change are filters.

[SOLUTION]

wooot! after months i finally found the solution. it was because of my kaskerspy antivirus. all i had to do was disable web anti-virus and it worked =D. this solved the same problem for many others also.