If I click on any k2 item link once, then continuesly click on it another time before item is loaded(sometime user may do it if it's slow), then I got 403 error page. See attachment for detail. I really need to have it resolved since it's downgrading my site right now.

This seems to be an issue that has to do with your server and not K2. If the page is loading slowly this may happen.
You need to check with your hosting company's help what is causing this slowness in your site and results in error pages.

I am keep getting the 403 error, the hosting company is very firmed that this is Joomla/k2 problem. I really need help since it's holding my site right now. See attachment for error and how to reproduce. My site is www.nybsnews.com. Please have a look before you say it's a hosting issue or k2 issue.

You seem to be using a very old version of K2 and it's K2 (v2.5 SVN) .

The latest version of K2 is v.2.6.7

getk2.org/downloads/?f=K2_v2.6.7.zip

Can I just go ahead and update it? It there any possible issues?

Hello Brahmasatyam,

Thank you very much for your help. I installed the new k2 and 403 error seems go away, which is great :) . But right now, I have other problems. Suddenly I saw there is a '1' on top and bottom of each item in each category, you can see it by click on the second menu button from left to see the problem, also the video picture is out of it's original position(you can see it by click on 5th menu button from left.)
Also the performance become a concern, each time I retrieve an item in the top left module in the home page, it seems very slow.

I still need your help. Please take a look in your early convenience.

Thanks
Kevin

I just find another problem, once I try to login from front end, I got 404 error, I got the same error when I tried to create a new user.

That 1 thing is caused by a plugin, try disabling it - see this post getk2.org/community/New-to-K2-Ask-here-first/11741-Strange-character-appearing-everywhere

As for the video picture, i do not know what is the original position you're referring to ?

What other components do you have installed? and what's the joomla version?

My Joomla version is 2.5.11

I don't have content - Roksocialbutton plugin installed, I tried to turn off a couple of plug in, but it doesn't help. I attached all the plug in status to you. Can you please help figure out which one I should try next.

Also the k2 user login module stop working now, I got 404 error whenever I click on it.

I am waiting for the help now, I need to get rid of the '1' thing. :( Please help!!!!!!!!