GC collecting "too much"..

[simendsjo]

I'm doing some coding against a c library, and Ds GC keeps collecting c  
owned objects (I think - disabling the GC makes everything work)
But how can I figure out what the GC is (read: I am) fucking up?
I have some to!string(c_struct_field) and format("%s", c_struct_field) and  
field = c_fields[i] etc etc