There are many reasons why the application may crash. It would be really helpful if you provided your computer specs. Available RAM, CPU speed and type, Disk space and fragmentation, applications that are running, and the version of MEP thay you are using all have a impact on why the application may crash. You have really provided none of this information. The best way to help us find a solution would be to provide this information.
You can't really just say "why does the software crash" without giving more detail. I could give you a hundred reasons as to why it might crash, but if you provide the correct information, the reasons would be much more applicable to your situation.
My install keeps crashing, too. I have Windows 8.1 on a brand new Dell XPS8700SE. 256 GB SSD (<50% populated), 32 GB RAM, Radeon video card, SoundBlaster Zxr sound card, 3 TB 2nd drive. I installed MEP 2015+ before, but was having the issues that required uninstall, then uninstall MS SU KB2918614, then install MEP 2015+. I have tried the install with my AV on and off. I have done the update after each install. The very first time I did the install, I did not get crashes. I just could't burn DVDs that played in any DVD players. I get:
and crash log states:
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MAGIX Movie Edit Pro 2015 Plus 13.05.2015 20:07
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CrashDump 20150513_200721_v14.0.0.176.dmp successfully written
Error in module "Videodeluxe.exe" (Load address: 0x0000000140000000) to address 0x00007FFA408051EA
Exception 0xc0000005 "ACCESS_VIOLATION"
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MAGIX Movie Edit Pro 2015 Plus 13.05.2015 20:17
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CrashDump 20150513_201755_v14.0.0.176.dmp successfully written
Error in module "Videodeluxe.exe" (Load address: 0x0000000140000000) to address 0x00007FFA408051EA
Exception 0xc0000005 "ACCESS_VIOLATION"
Processor [46] 3592MHz 4 Core(s)
Microsoft Windows NT 6.2 (Build 9200)
Used Memory: 710 MB Max Used Memory: 715 MB
Free Virtual Memory: 38624 MB Total Virtual Memory: 131072 GB