Recently, I found that since, as they write, "We've improved our site," I was unable to use Citicard's web site to pay my Mastercard. After finding the solution, and complaining about it on a couple of forums and mailing lists, a few people posted back to say, Thanks for giving the solution. Therefore, I'm posting the problem and solution here.
Googling indicates that several people simply cancelled their Citibank cards and used other cards with websites that work. In the end, that's what I did as soon as I found another card, (in this case, Amex) that gave the same cash back deal as Citicards. I didn't cancel my card, but I don't use it. For awhile, however, Citibank had the best cashback deal of the cards I had, so I kept using them. Hopefully, someone from Citibank will see this page and realize that their website is costing them customers. If you're a Citibank person wondering about that, put citicards.com linux in a google search box. In the first 20 hits I found, at least two were about people cancelling their Citibank credit card because of this. I'm another who will no longer use the card, because I see no reason to be inconvenienced by your website when other credit card companies are offering me the same value without having the inconvenience of dealing with your site.
Also, Mr. or Ms. Citibank person, yes, I did call your tech support, to be politely told that they don't support Linux. When less than two minutes of googling brought me the solution, I wrote, using the web contact form, to tell them that when they get such calls in the future, here is the solution. I received back what seemed like a form letter, telling me they don't support LINUX. (They put it entirely in uppercase.)
One would think that with their various troubles, Citibank would be more concerned about alienating and losing customers, but that's the way it goes.
This page started out to be a rant about how silly I thought they were, etc., etc. However, most people who find this page probably just want the solution and are already aggravated enough.
When you log into citicards.com, you'll see the log in screen. Then, in a few seconds, it will change to a page that is basically a white blank with a few things at the bottom. It's apparently caused by an old flash bug.
I had more involved solutions of temporarily turning off flash or javascrpt, but there's an even simpler way to fix this. Right click anywhere inside the white screen and choose Play from the menu. An advertisement will appear. Click the X in the upper right of the advertisement's box, and you are back at the login screen. Thanks to the poster on Fedora forums who pointed this out to me.
The other solution is to either temporarily turn off flash in your browser or to use https://www.accountonline.com/View?docId=Login&siteId=CB to log in.
If one uses Linux, as of late December, 2007, although you see the big blank white page, there is one of those annoying floating type ads. If you click the x on the floating window to close the ad, you will get to the login screen. In FreeBSD, however, I'm still just seeing the blank white page.
Googling for something like citicards.com linux will give you a bunch of rants about it, so I'll just leave it at that. (There are other solutions too, but the right click then clicking play or using the alternate site seem to be the easiest ones.)