themoron :@)
The rest of the problem is caused by the special code string Google inserts in front of ad headlines, but only for ads where the advertiser is using Google's conversion tracking. That's why some ad headlines display properly and are clickable, and others are not displayed, and therefore are not clickable. The offending code string looks like this:
href=/pagead/adclick?adurl=...
The problem is the string "adclick". Norton AdBlock includes this in the list of strings that will cause an ad and all of its associated hyperlink code to be blocked. In fact, Norton AdBlock strips the entire offending href block from the page before the page is displayed.
A localized solution is to use the advanced configuration option in Norton Firewall or other AdBlock supporting product to remove the adclick entry from the ad blocking string list. However, the bigger issue is that this problem will occur on every Google search results page with conversion tracked ads, if the user has Norton AdBlock enabled. The effect on AdWords advertisers is that those who start using Google's conversion tracking will see their CTR decline even as impressions remain at normal levels, which eventually affects their ad's position and costs.
I have reported this behavior to Google Support just recently. I hope that they will decide to change the adclick string to something else that will not trigger Norton AdBlock, since I don't think its reasonable to expect hundreds of thousands of Norton AdBlock users to re-configure their AdBlock parameters just for this, or for Norton to remove the "adclick" string from their standard list, since there are probably good reasons for it being there to block other ads.
