Sounds to me like your computer hardware is giving up or overheating, either that or some driver dosnt like TFS and decides to freeze windows.
First of all i suggest you download and run memtest to make sure your ram isnt going to hell
Memtest86+ - Advanced Memory Diagnostic Tool
Secondly i suggest you check your harddrive's S.M.A.R.T readings to make sure its not that which is on the verge of crashing, any program which does it would suffice.
Personally however, i suggest hdtune, its free and tells you basic info
HD Tune
Thirdly i would suggest that you download a program which keeps track of your CPU (and maybe even your GPU) temprature, since an overheating CPU/GPU can also cause this problem in some cases (which is usually caused by, yes you guessed it, fans clogged by dust), for this i suggest hwmonitor.
(Keep the program running and visible when you run your server, and when it freezes, look at its last readings and see if it displays some crazy readings like 110C CPU temp or something)
CPUID
If none of these things gives you any solution, my suggestion is to format your computer, begin with a fresh install of your OS, and see if it solves the problem, since sometimes, old/bugged drivers, viruses and old programs, and even a messy registry can cause these kinds of problems.
