must question

[abufletcher]

How about:

"I must have to do it differently, because what I've been doing so far sure isn't working." ((Which BTW sounds fine to my American ears))

But if that still sounds a little weird to others how about:

"I must need to do it differently, because what I've been doing so far sure isn't working"

And if that DOES sound better, try explaining grammatically why you CAN use "need" here but not "have to" when "I need to study" and "I have to study" would usually be treated as equal. BTW, to my ears "I must hafta do it" sounds a whole lot more acceptable than "I must have to do it." I'm not sure why but I suspect it has something to do with the "chunkiness" of "must have" conflicting with "have to do it" while the other pronunciation allows mental chunking as (must)(hafta do it).

I suspect that they only real "grammar" problem here is infrequency of use.

[Stephen Jones]

Grammar problems can all be put down to 'infrequency of use'. If the constructions in question were used frequently by native speakers, they would be grammatical by definition.

Of course the converse is not necessarily true. Rarely used phrases can still be grammatical, as in the case of "I saw it for the first time".

[abufletcher]

I basically agree but I quibble with the phrase "grammar problem." I would contend that there is nothing whatsoever "grammatically wrong" with "I must have to do it." The only "problem" is that it does not occur frequently enough for even highly skilled speakers of English to readily imagine a context when it is spoken out of context adn thus think is sounds "strange" which they have been trained to think equates with ungrammatical.

BTW, in rejecting the existence of Language (with a capital L as discussed in the Matrix thread), I also reject the concept of "native speaker." People just have more or less experience with a lived-language.