You are making a lot of assumptions. This has been a problem I have seen personally for the last four years on many different versions of Modelsim and many different computers. My coworkers in another company also saw this problem and explained to me that it was a known bug in Modelsim that was caused by a memory leak.
I am just a dumb engineer who finds that one in 30 times as I recompile a design and start to reload it, the Modelsim window disappears and I have to open a new one only to find my last edited modules need to be recompiled again. I seriously doubt that it is related to my design in any way (unless my style is really that bizarre) or my computer(s) or if it has to do with how long the window has been open or how many times I have reloaded the same files. I just know it crashes more than I would prefer.
Has no one else seen this?