Let Λ be a lattice in a second countable, locally compact abelian group G with annihilator Λ ⊥ ⊆ G. We investigate the validity of the following statement: For every η in the Feichtinger algebra S 0 (G), the Gabor system {Mτ T λ η} λ∈Λ,τ ∈Λ ⊥ is not a frame for L 2 (G). When G = R and Λ = αZ, this statement is a variant of the Balian-Low theorem. Extending a result of R. Balan, we show that whether the statement generalizes to (G, Λ) is equivalent to the nontriviality of a certain vector bundle over the compact space (G/Λ) × ( G/Λ ⊥ ). We prove this equivalence using a connection between Gabor frames and Heisenberg modules. More specifically, we show that the Zak transform can be viewed as an isomorphism of certain Hilbert C * -modules. As an application, we prove a new Balian-Low theorem for the group R × Qp, where Qp denotes the p-adic numbers.