Yeah, we all got that today.
It could be a false warning, those have been known to happen. The Safe Browsing diagnostic page gave this report:
Safe Browsing
Diagnostic page for pantheranetwork.com
What is the current listing status for pantheranetwork.com?
Site is listed as suspicious - visiting this web site may harm your computer.
Part of this site was listed for suspicious activity 1 time(s) over the past 90 days.
What happened when Google visited this site?
Of the 3 pages we tested on the site over the past 90 days, 2 page(s) resulted in malicious software being downloaded and installed without user consent. The last time Google visited this site was on 2011-04-10, and the last time suspicious content was found on this site was on 2011-04-10.
Malicious software is hosted on 1 domain(s), including globalpoweringgathering.com/.
This site was hosted on 2 network(s) including AS8182 (DIGITALRIVER), AS26496 (PAH).
Has this site acted as an intermediary resulting in further distribution of malware?
Over the past 90 days, pantheranetwork.com did not appear to function as an intermediary for the infection of any sites.
Has this site hosted malware?
No, this site has not hosted malicious software over the past 90 days.
How did this happen?
In some cases, third parties can add malicious code to legitimate sites, which would cause us to show the warning message.
Next steps:
* Return to the previous page.
* If you are the owner of this web site, you can request a review of your site using Google Webmaster Tools. More information about the review process is available in Google's Webmaster Help Center.
If it's a real risk, I'm sure the advertiser will look into what's causing the problem and get it fixed. I feel bad for them though if it's a false report... that happened to a friend once and it took a month for that warning to be removed.