Recently released v1.7.3 appears to be unstable in R pre-2.14.0. Post 2.14.0 it's fine I believe. Looking into a fix ... The over-allocation in 1.7.3 uses truelength. This is initialized to 0 by R 2.14.0+, but not initialized in pre-2.14.0. Thought I'd worked around that but seems not. Matthew