The Portuguese prefix "des" tantamount to the English prefix "un", so, it would be a "un-bug".. Like 'untie'='desamarrar', 'to debug'(verb)='desbugar'. (so it probably could be unbug XD). I feel that the 'un' mean to eliminate or to reverse (like 'undead', in Portuguese, it would be translated as "desmorto" (so an 'undead' would be an dead person 'unkilled', 'dekilled' or 'diskilled'

), but in Portuguese (in Brasil at least) people say "morto-vivo" (which would be translated as "living dead")).
But there are some cases in the English that are quite similar i suppose, cases like 'to detach'='destacar', 'to degrade'='degradar'.. i think that those came from old borrowed words from Latin, French, Italian and Portuguese. (i suspect that 'debug' follows that line of thought). I suppose 'de' would mean to lower the intensity of presence (on the examples, of the attachment and grading).
Another prefix that i feel as similar as "un" and "de" (Portuguese "des") is the English prefix "dis", as in "discontent"="descontente", or "to dislike"="desgostar", i think it would 'reverse' the meaning of the original word. A 'disbug' would be... :?:mmm:?:.. something useful and good that came originally from a bug?
About the 'items'='itens'(Portuguese), there is a rule on Portuguese grammar that says - 'M' only goes before 'P' and 'B' (or of course, in the end of the word).
A very interesting thing i remembered (thinking of 'undeads' and stuff XDD) is of Zumbi of the Palmares (leader of the Palmares Quilombo (quilombos (read as 'kilombo', and Zumbi as 'Zum-bee') were places where black fugitive slaves settled a resistance, self-sustaining hidden communities, quilombos exist till today, and people who live on quilombos are called 'quilombolas'), the word 'Zumbi' can be translated as "ghost" or "specter", but also as "Alive Spirit" (the term 'spirit' was seen as different from 'soul', since (according to Paracelso) the 'spirit' is related to one's volition (or 'gases' or 'breath of life', indirectly tangible), and 'soul' is related to the presence of God within a personality, in this sense, a spirit can be vanished, sold, or transform, but the soul is one and only, can not be sold or killed, the Soul is completely intangible and transcendental, metaphysical) Zumbi of the Palmares was very feared among the slave-drivers, very charismatic, strong, and skilled with the spear, till today Zumbi of the Palmares ('Zumbi dos Palmares' in Portuguese) is revered as a great leader and symbol of resistance to the oppressed (especially black people)... XDD