Upon opening new account…

After a weekend upgrade, Yahoo's search engine ad system first slowed to a crawl, and then went belly up on Monday, preventing marketers from making changes to their campaigns, accessing their accounts and, in many cases, even having their ads run at all. Yahoo support representatives are telling clients that they themselves can't access their accounts and have no idea when the problem - now in its third day - will be fixed.

Yahoo search spokesperson Gaude Paez told MarketingVOX Wednesday evening that the upgrade caused "unexpected issues," and that their engineers were working around the clock to fix the problem.

The problem appears to be affecting small and large clients alike. Calls made yesterday to personal service reps that deal with the larger clients have gone unanswered.

Attempting to open an account as late as 8:30 p.m. Wednesday resulted in the error message seen in the graphic above.

Search listing ads continue to run on Yahoo, but many have simply stopped. One Yahoo client said that a service rep told her that they could discern "no rhyme or reason" as to why some ads continued to run and some did not.