Win7 x64 Facebook error, just started today.

[Edward78]

Firefox can't find the file at jar:file:///C:/Program Files (x86)/Mozilla Firefox/omni.ja!/chrome/browser/content/browser/undefinedcheck6only.facebook.comajax/v6.php?v=check6only&pingonly=false.

 

[no_sleep_til]

i can't help with regards to the missing .jar file, but for me W7x64 the site is working as normal. possibly a noscript/adblocker-type problem? unlikely, but just to confirm that the site is ok in relation to your o/s

 

[Paracelsus]

Looks like a problem with your browser. Try clearing the cache, updating plugins and if that doesn't work reinstall it