Recently (no idea when it started) there is large text hyperlink shown up when I'm on Yahoo! Mail.
How to get rid of that?
It's ANNOYING and I'm PUZZLED why Yahoo! do that... It's probably just Yahoo, they support themselves partly with ads.
Nothing you can do about it, although you COULD try Firefox with Adblock Plus and a filterset updater.It's not only annoying.
Although it only appears in certain mails (and Inbox!), but for those pages that they appear, all the buttons (Delete, Reply, Forward, etc.) are not responding!
I'll have to open the mail in order to do anything with it, which I cannot do in Inbox interface.
And for those mails that is affected, I cannot do anything with the mail.

Inbox


Affected Mail


Non-affected Mail
Not having used Yahoo, I can't say if that's normal or not, although I'd be surprised if it was.
How about on a different computer, is it the same?
What browser are you using?It's absolutely not normal.
I couldn't try on another computer because I only have one in my house.
I'm using Firefox.Definitely not normal. What's your OS? What protection do you have?My OS is Win XP SP2.
I have Norton Antivirus, AVG Anti-spyware, Spybot S&D.
I don't THINK it has anything to do with virus or adware since it only affect certain mails.
It just seems that the hyperlinks are displayed in very large font rather than normal one, and that the buttons are not working.
Download CCleaner (install without Yahoo! toolbar) and configure it according to this GUIDE. Make sure you also set it to clean out your Firefox files.

Update AVG, reboot into Safe Mode, and perform a full system scan. Let it clean whatever it wants. Restart your computer and post the log here.

Then download HijackThis and post a log for us to take a look it.

It may or may not be an infection...this will help us determine that.