This worked for me after over an hour of Resumes, Load Games, Repairs, config and Option changes, etc... I was playing the Trilogy version of ME2 on a quad core laptop running win7.
I went to the Citadel with Garrus and Thane to do their loyalty missions. I was doing Thane's first and always crashing at the end of the Illusive Man's summary. I finally decided to do the Garrus mission first and there was no crash. I remember doing Thane's mission first seemed to flow with the dialog and it seeming awkward to do it second.
My solution fits a particular situation but if yours is different, it might still suggest something to try.