The best place to tướng start is "the usual" --
When you have a problem with one particular site, a good "first thing to tướng try" is clearing your Firefox cache and deleting your saved cookies for the site.
(1) Clear Firefox's Cache
See: How to tướng clear the Firefox cache
If you have a large hard drive, this might take a few minutes. If you vì thế not see the number going down on the page, you can reload it using Ctrl+r to tướng kiểm tra progress.
(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:
- right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "View Cookies"
- (menu bar) Tools > Page Info > Security > "View Cookies"
- click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Cookies" button
In the dialog that opens, the current site should be pre-filled in the tìm kiếm box at the top of the dialog sánh you can remove that site's cookies individually.
Then try reloading the page. Does that help?