HP49-50G: MLSV OK for -1E-495, not OK for -1E-496, ROOT OK for both

[Gil]

I have a program and may get a complex number, for which I look for a solution.

The function is x*EXP(x).

I want to solve x*EXP(x)=-1E-495.

With ROOT
'x*EXP(x)+1E-495' (in stack level 3)
'x' (in stack level 2)
-1000 (an approximate guess in stack 1)
ROOT
and the output: -1146.82437196

With MLSV
['x*EXP(x)+1E-495'] (in stack level 3)
['x'] (in stack level 2)
[-1000] (an approximate guess in stack 1)
MLSV
and the outputs:
[ 'X*EXP(X)+1.E-495' ]
[ 'X' ]
[ -1146.82437276 ]

Fine, the final result found with MLSV is almost the same as with ROOT.

Now repeat the two exercices for x*EXP(x)=-1E-496

With ROOT
'x*EXP(x)+1E-496' (in stack level 3)
'x' (in stack level 2)
-1000 (an approximate guess in stack 1)
ROOT
and the output: --1148.9899614

With MLSV
['x*EXP(x)+1E-496'] (in stack level 3)
['x'] (in stack level 2)
[-1000] (an approximate guess, even --1148.98 or -1148.9899614, in stack 1)
MLSV
and then an endless "search" will occur, with no output.

Why?
And is there a way, in this case, to get the wished value of about -1148.99 with the MLSV (as already mentioned, I am not supposed to know, beforehand, that x is a real and that I can use instead ROOT command without the brackets) ?