An unknown problem is just that. It is a problem that is unforeseen or that a person is not aware of. When there new programs being release there are sometimes problems that are unknown.
it depends on the context initial (as your initials) - Initial initial (as in first) - erste/erster/erstes
what is initial correspondence
My first initial is A.
Initial
initial speed means first
The initial concentration of A was 0.05 M.
The plural form of initial is initials.
No. He/She cannot initial
The answer to what is Georgia's initial is GA, because Georgia is the state and Atlanta is the capital.
Design process requires initial idea. Initial idea should match with our requirement.
initial - final / initial x 100
Follow that initial(!)- with a period.