Q:

Windows defender suddenly started to delete my exe while other anti virus programs say ok, i don't understand why? 

It was fine few months ago.  but then suddenly "windows defender" and "windows security essential" are starting to delete my exe and say it is a Trojan:win32/...
But all other antivirus programs say my exe is fine, no virus detected. 
What's wrong on earth? 
My exe locates in a same folder with other exe files, all exes are written by me in c#, and copies some file and acts like an updater. 
My other exes are fine with windows defender and security essential.  But only that one exe, acts like updater, is look like malware by them? 
What should I do? 

A:

Antivirus programs use algorithms that attempt to predict whether an unseen program contains a virus.  They do a great job overall but sometimes get it wrong. 
Each major antivirus maker has a means to submit a false positive (your exe in this case).  For Windows Defender:
https://www.microsoft.com/en-us/wdsi/filesubmission
In my experience, false positives are often corrected within a few days.