  We study the superpotential induced by Euclidean D3-brane instantons carrying
instanton flux, with special emphasis on its significance for the stabilisation
of Kahler moduli and Neveu-Schwarz axions in Type IIB orientifolds. Quite
generally, once a chiral observable sector is included in the compactification,
arising on intersecting D7-branes with world-volume flux, resulting charged
instanton zero modes prevent a class of instantons from participating in moduli
stabilisation. We show that instanton flux on Euclidean D3-branes can remove
these extra zero modes and helps in reinstating full moduli stabilisation
within a geometric regime. We comment also on the F-theoretic description of
this effect of alleviating the general tension between moduli stabilisation and
chirality. In addition we propose an alternative solution to this problem based
on dressing the instantons with charged matter fields which is unique to
F-theory and cannot be realised in the weak coupling limit.
