Suddenly Stopped Validating

I am starting a new thread because my other question was buried in someone elses thread (sorry for the hijack dutch_advertiser ).
My site is http://www.getonmyspace.com/
I have tried 5 fresh sets of the coop php pages and changed the code accordingly every time in my footer to no avail.
Text file is set to 777
The only thing I changed (apart from adding new content which has always been the same method) is put Valueclick ads on there (1 pop and 1 interstitial) about a month ago but having said that it was validating with no problems after I added them (checked that on more than one occasion).
I am really at a loss as everything was ok for months.
The only thing I do notice which might be a clue is that before when I updated validated/calculate weight it always took about 3 or 4 seconds to do whereas now it takes about half a second and always comes back with Ads not found.In my stats there are still impresssions showing up to April 7th the last date on the graph.The ads are definately on my page and the txt file is filling up with no problem.
Any help would be greatly appreciated.
Thanks for reading
MK

 

My biggest account has stopped validating too, even though ads are running fine of course.

First weight dropped from 80k to almost 0, and now it won't validate at all.

 

I wonder if something has changed within the co-op.

 

I got an email this morning telling me it couldnt find the ads on my site too. Nothing has changed code-wise, and the ads are very much there. If i manually tell it to re-validate, same error. grr.

 

I get revalidation emails quite often too...haven't seen an effect on my impressions though so i'm not worried.

 

That reminds me of a question I've been meaning to ask.
When you click on stats by an ad is that the number of times your ad has been shown on other sites?

 

Yes it is.

 

Thanks BlueDevilMedia.I am still getting impressions but no weight or validation

 

You can't get impressions if you are not validating

 

In that case I am now totally lost (easy with me)
Definately no validation or weight but also the graph is definately 100% showing impressions.
They show right up until the 18th april But are declining steeply.

 

If it continues to not validate then yes impressions will drop sharply with in a few days but not immediately.

 

Thanks for the reply Shawn.At least I know now why.I will get on to my host as they have obviously changed something.
Appreciate your time.
Thanks
MK

 

It is now working on my site
My hosts had oviously changed/updated something and this was there solution.
"Hello,
I have disabled this secfilter in mod_security, please let us know if you need any assistance in this matter."

Thanks to all you guys that helped..especially to Shawn who took some time out to look at it.

I hope the other sites that suddenly stopped validaing for no apparent reason can benefit from this.
Good luck
MK