3 easy quick things to try. I suspect overheating, this is summer time in many parts of the world and this can happen. So, make sure you computer is getting air around it and isn't clogged up with dust bunnies!
Did you try TPing to another sim? Try and empty on in the ocean, ANWR is pretty light build so try going there. Enable the choice of sim you log into by changing these settings in the preferenfces menu
Lower the screen resolution before you start up SL, this will hopefully let your GPU and CPU run cooler and give you time to take off the dress and eliminate it from the list of trouble OR prove it's the culprit! Monitor settings usually are where it is at. Write down the settings you have now, then lower it, no lower than 800X600 because the SL viewer UI is hard to use at this point. Does this stop the crashing?
If you are worried still, if it is hot and you belive it is heat then you could try lowering the SL settings in the preferences window. Me>Preferences menu or press cntrl key + p key.