I have a fairly large surface model I'm working with (almost 2000 features, ~100mb) and I'm having a lot of problems with forced rebuilds (ctrl+q).  I can open and work with the model just fine, but sometimes I do a forced rebuild and some features will rebuild with errors even if they were perfect before.  In most cases I can edit the feature and reselect the exact same features that were highlighted in red or yellow and it will rebuild fine. Other times I'll have to delete a sketch segment and redraw it or re-convert it from another feature.  I don't understand why it does this.  I spend hours and hours per week redefining features and the redundancy is killing me.  And the worst part is that it seems like it does it with no rhyme or reason.  There isn't one or two features that consistantly fail.  One time I'll rebuild and features "A" and "B" wont rebuild correctly, then the next time it'll be features "C" and "D" that will mess up.  I don't know if this is a bug or if it has something to do with my model.  Any help is appreciated, below are my system specs

Intel i7 2600k

msi gd65 board

16 gb ram

1 tb hdd

nvidia quadro fx 1800

SW 2k11 sp 3.0

Thanks,

Tom