Links from Gmail are not opening anymore in a new tab or a new window

A couple of days ago, clicking on a link from a mail message received in Gmail, stopped working. I click on the link, and in less than a second, a new tab opening and then closing. The only way for the link to open is if I right click the link, and chose "open link in new tab". I haven't changed anything in firefox's preferences, and tried adding the address "https://mail.google.com" to the allowed pop-up windows list in the security section of the preferences. Still no change. Please help me :)