Mingleforum Seo Friendly Links Option Makes my Property Listings 404

hi there,

i am using smooth wordpress theme for real estate website. i use permalink structure as /%Postname%/, when i activate seo friendly urls option in mingleforum options, the forum is ok but my property listing which are structured as manahilestate.com/property/some-property-listing/, all become 404, they display but when i click to open any post, they are not found. so i disable seo friendly urls option and go back to permalinks and save the structure again as /%postname%/ and my property listings work fine. my forum is located at http://manahilestate.com/forum/ .
i want a solution in a way that my property listing are not broken and the forum gets seo friendly links,rather than the default short link.
I have tried searching this issue in your support forum as well as here,but no solutions are mentioned anywhere.

kindly help.

Regards

http://wordpress.org/extend/plugins/mingle-forum/