Here is the update. I replaced that ad with another one and now it works!
Then I replaced this ad with the original one (which was not displaying) and now it works too!
Then I simply deleted one line from above adsense code and the ad it gone again....this is how it was as shown below...

THIS IS MY TEXT

<script language="javascript">
THIS IS GOOGLE ADSENSE CODE
</script>

and I changed it to this

THIS IS MY TEXT
<script language="javascript">
THIS IS GOOGLE ADSENSE CODE
</script>

and the ads were gone again.

Then I gave that line again but ads won't display. Then I had to replace it with another ad and now it works again.

This happens to my sites at times. It scares the $%^& out of me when it does.

What I do is to go to another site that has adsense on it [not mine] and see if adverts appear there. If they do, I do back to my site and they then show up.

Scare over, and a big sigh of relief.

Techman,

Over the past week or so I have noticed ads disappearing from my sites. When they go away on one they seem to go away on all. They come back without my taking any action.

As far as changing the AdSense code as you mentioned, that's in opposition to the AdSense policies and could get you in trouble. I wouldn't do that.

FarmBoy

It doesn't look to me like techman changed anything harmful, only removed a leading space before the adsense code, which I can't imagine would make one bit of difference either way, anyway.

However, I would say having behavior like this occasionally, especially for new pages, is normal. Google has MANY servers (more than Carter's got pills...) It is normal to see something working and then for no reason see it not working, back and forth like this, for a period of time. This is most likely due to the various Google servers updating and catching up with each other.

Yes I didn't change Adsense code just removed the line above it.

guys, there is something very strange going on with adsense.
just accidentally noticed that my ads are not anymore displaying in opera all at once.

well they are live-testing their messy code on the publishers again: javascript error.

guys, there is something very strange going on with adsense.

Related thread - [webmasterworld.com...]

You're not alone.

FarmBoy

I had the same phenomenon. Ads quit displaying in FireFox -- for only one site! -- but were displaying in IE. It happened sporadically. Go figure.

YM

ads are still not displaying in opera. honestly, i'm sick of reporting such fuss to google every time it happens. the problem is 100 percent on their end, because the browser error console shows me a javascript type mismatch error that obviously causes the ads in my leaderboards not to display.

google, get your act together! is a cross browser test with your adsense javascript code too much to ask for? how can it be that this isn't alerted with some kind of warning system or in their stats? dump!

One of the joys of AdSense is that we have to guess what is happening, and our guesswork is often completely wrong because we don't have the necessary facts to make even educated guesses. My current wild speculation is that Google is tweaking its "unsafe content" filters, perhaps in association with the introduction of third party ads to its network.

My ads have disappeared again. If it holds true to form, they will be back in a few minutes.

FarmBoy

One more thing that I have noticed that on my home page the standard image banner 468X60 on top displays public service ads about 80% of the time!
I mean what the hell.....There are plenty of content on home page related to microsoft, business, hard disk, google, health e.t.c and Google can't find a single ad related to it! I am really pissed off now.
On the inner pages though the frequency of public service ads on top banner ad is low and the other two ads one link unit on left side menu and other text unit in center almost never display public service ads.

It's only the banner ad on top of home page that displays public service ads most of the time I don't know why.