Seems par for the course when Yahoo is concerned.
It's not aimed at YahooSarah, Yahoo is just awful at dealing with large numbers of keywords.
Our Google account has a 1 Million keyword limit and we can call our rep when we need more campaigns.
Our Adcenter account reached 600,000+ keywords before the reps couldn't get it to accept any more.
Just 12,000 keywords accepted from around 400,000! And we know they work (otherwise we would not have custom built a spreadsheet generator for YSM)
Yahoo also handles broad match really badly.
The annoying thing is that the terms that do work on YSM give us great ROI, we just want to spend more. Seems that having a personal rep does not help with YSM either. We had a Platinum or Diamond account status (can't remember which - but the highest one - which entitles you to a rep that deals with only a few dozen accounts) yet we still could not figure out how to spend more.
I really hope things change for the better. soon.