If I write {tubItchoHmoH} then what does it mean ?

 

"You begin to cause me to be nervous"

or 

You cause me to begin (i.e. you cause that I begin) to be nervous ?

or can it mean both ?

It can mean either.

When you've got -moH, you have to be careful when deciding whether the other suffixes refer to the causer or the doer of the action. It can be either. Context will tell.

-- 
SuStel
http://trimboli.name