indyank - 4:09 am on Aug 19, 2011 (gmt 0)
Staffa, do you have a Bing webmaster tools account? If not try creating one and set the crawl rate.
Also check whether you have something in .htaccess file that blocks their bots. More importantly, ensure that what you see as bing bot (MSNBot) are those from their range of IPs.