I have heard that there are some issues b/w text-link-ads and Google PR, is it the same with kontera.
Basically I want to know is it safe to use Kontera advertising system on my blog, as I don't want to loose my PR !

never heard of "Kontera" what is that?

PR is just a green bar that shouldn't be prioritized. As for the text-link-ads, and the Kontera you are saying, I don't see any good thing on using it. Better work on other things than focusing your time on getting some good Green PR Bar. :|

Pr is just the green bar that calculates site importance from 0 to 10, though i don't understand what kontera is and didn't know the relevance of kontera to PR!

I think its a website, I search in google and I see Kontera.com offers pay per click service.

I had use Kontera a year ago. Sad to say, its really hard to earn money from it. Plus, it slow down your page loading time. So, I just remove it.