Really all I can suggest is you drop down to UM16.04 and see if that runs smoother, 16.10 is very buggy and I only installed it on a test partition to try and help you!. 
Thanks for the advice and the effort (in fact you could have instlled it in virtual box, much safer and faster). Is that topmenu working in 16.04? If it is, I’ll downgrade then
Btw why did you say 16.10 is buggy? I think other than the topmenu, everything is working for me.
I had problems with the GPU drivers and some of the theming is shot imo!. 
Do you think if there is a chance for this to be fixed soon?
Maybe but don’t forget that UM16.10 is only supported until July 2017 so quite possibly; by the time the fixes have been applied, the support will stop?.
Hello.
My Ubuntu MATE also encounters a crash by manipulating the top menu at 16.10 and 17.04. 16.04 LTS is normal.
Perhaps it is a bug that occurs under certain conditions,
and it is a situation to report a bug to Launchpad again.
I found this report at Launchpad. You probably have encountered this bug:
https://bugs.launchpad.net/ubuntu-mate/+bug/1630515
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These Crashes appear in debian 9 stretch too - Caja, Pluma, Terminal … but not GIMP, or Audacious, which are GTK2 apps.
Seems it happens on GTK3 apps only. Too bad that the whole MATE switched to GTK3.