Just adding my 2 cents.

Is the 1440P computer cpu slower and have less memory. 50K lines is a fair amount, but I work with 70K lines often. Unless I am trying to do many calculations and intense cpu resources, I do not have this problem and I do, it usually not lock up (might be delayed). I have had it lock up, but I realize that I had a lot of other programs running at the same time and I have closed the other programs.

To me it sounds like you have the computer optimized. One question is when this happens, what is going on in the task manager? Is the CPU, hard drive, etc. maxed? It would be interesting to see how it is killing the system.

For me, I would think that it is a memory issue, but yes drivers could be causing the issue. I have had issues with drivers causing odd things on my system (not with excel) and yes you can call me lazy, I use 2-3 different driver updater programs. Why so many? It is more of a matter making sure I have the latest driver for everything (sound, video, etc.) and I find each program to be better in certain areas on getting updates. I just use the free programs.

I know this post is a lot of questions and comments, but I wanted to give you my 2 cents.

RadicalROM