I have a drawing that was created with no problems. A moderately large assembly broken down into seven pages of drawings. After the drawings were completed, a meeting with the customer revealed a need for some changes. I made the changes to the model and went to open the drawing to update it and everytime I try to save, it seems to lock up. I have opened task manager and found that I'm not using more than 14% CPU time while waiting for the save. I have waited up to two hours for the program to complete the save before shutting it down and restarting it. I have SW 2012 64Bit installed on a i7 quad core laptop with 32GB ram and an NVidia Quadro K2100M graphics card. While watching task manager, one thread is working 100% while the others are idle. Then the other threads will go active while the first one takes a break for a little while (presumably forced by windows or some firmware on the machine to prevent thermal issues). Then it goes back to one thread doing a full load while the others are idle again. During all of this, overall CPU usage never shows more than 14%. Does anyone out there know what exactly is going on here and why SW is not actually utilizing all 8 available threads (virtual cores)? If there wasn't such a time crunch here, I would use my SW install disks as a frisbee and start from scratch with Inventor.